Field Induced Chirality in the Helix Structure of Dy/Y Multilayer Films and Experimental Evidence for Dzyaloshinskii-Moriya Interaction on the Interfaces
S. V. Grigoriev, Yu. O. Chetverikov, D. Lott, and A. Schreyer
Polarized neutron scattering experiments have demonstrated that Dy/Y multilayer structures possess a coherent spin helix with a preferable chirality induced by the magnetic field. The average chirality, being proportional to the difference in the left- and right-handed helix population numbers, is m ... [Phys. Rev. Lett. 100, 197203 (2008)] published Fri May 16, 2008.
Pressure-Induced Superconductivity in CaLi[sub 2]
T. Matsuoka, M. Debessai, J. J. Hamlin, A. K. Gangopadhyay, J. S. Schilling et al.
A search for superconductivity has been carried out on the hexagonal polymorph of Laves-phase CaLi, a compound for which Feng, Ashcroft, and Hoffmann predict highly anomalous behavior under pressure. No superconductivity is observed above 1.10 K at ambient pressure. However, high-pressure ac suscept ... [Phys. Rev. Lett. 100, 197003 (2008)] published Fri May 16, 2008.
Joule heating in ferromagnetic nanowires: Prediction and observation
Kab-Jin Kim, Jae-Chul Lee, Sug-Bong Choe, and Kyung-Ho Shin
We present an analytic theory of the Joule heating in metallic nanowires. The steady state is calculated for heat conduction through the insulation layer and then the transient state is considered from the thermodynamics law. The temperature is predicted to exhibit a quick exponential decay to a ste ... [Appl. Phys. Lett. 92, 192509 (2008)] published Thu May 15, 2008.
Observation of spin-glass behavior in antiperovskite Mn[sub 3]GaN
Bo Song, Jikang Jian, Huiqiang Bao, Ming Lei, Hui Li et al.
The dc magnetization, ac susceptibility, and isothermal remanent magnetization measurements are carried out for antiperovskite MnGaN. Strong indication for a frozen state with freeing temperature of T at ~133 K is found, determined from the difference between field-cooled and zero-field-cooled magn ... [Appl. Phys. Lett. 92, 192511 (2008)] published Thu May 15, 2008.
Magnetic flux noise in MgB[sub 2] superconductor
Neeraj Khare, D. P. Singh, and Ajai K. Gupta
Magnetic flux noise in MgB polycrystalline sample is measured using a high-T rf-superconducting quantum interference device in the temperature range of 640 K. A small magnetic field (~200 mG) was applied while cooling the sample. The flux noise exhibits 1/f type of behavior with alpha~1.01.3 and s ... [Appl. Phys. Lett. 92, 192508 (2008)] published Thu May 15, 2008.
Temperature-dependent electronic structure of the colossal magnetoresistive manganite La[sub 0.7]Sr[sub 0.3]MnO[sub 3] from hard x-ray photoemission
Francesco Offi, Norman Mannella, Tommaso Pardini, Giancarlo Panaccione, Andrea Fondacaro et al.
We have studied in situ fractured surfaces of single-crystal LaSrMnO with hard x-ray photoemission (HXPS) at an excitation energy of 7.7 keV. These more bulk-sensitive measurements reveal low-binding-energy satellites in the Mn 2p, 3s, and 3p core spectra that are in agreement with previously observ ... [Phys. Rev. B 77, 174422 (2008)] published Thu May 15, 2008.
Magnetic properties of Fe-Pd magnetic shape memory alloys: Density functional calculations and epitaxial films
J. Buschbeck, I. Opahle, S. Fahler, L. Schultz, and M. Richter
The magnetic properties of Fe-Pd magnetic shape memory alloys with different Pd contents are investigated in epitaxial films and by means of density functional calculations. The magnetocrystalline anisotropy energy (MAE) of ordered and disordered Fe-Pd alloys is calculated as a function of c/a ratio ... [Phys. Rev. B 77, 174421 (2008)] published Thu May 15, 2008.
Interface magnetism in Fe[sub 2]O[sub 3]/FeTiO[sub 3] heterostructures
Rossitza Pentcheva and Hasan Sadat Nabi
To resolve the microscopic origin of magnetism in the FeO/FeTiO system, we have performed density functional theory calculations that take into account on-site Coulomb repulsion. By systematically varying the concentration, distribution, and charge state of Ti in a hematite host, we compile a phase ... [Phys. Rev. B 77, 172405 (2008)] published Thu May 15, 2008.
Chromium at high pressures: Weak coupling and strong fluctuations in an itinerant antiferromagnet
R. Jaramillo, Yejun Feng, J. C. Lang, Z. Islam, G. Srajer et al.
The spin- and charge-density-wave order parameters of the itinerant antiferromagnet chromium are directly measured with nonresonant x-ray diffraction as the system is driven toward its quantum critical point with high pressure using a diamond anvil cell. The exponential decrease of the spin and char ... [Phys. Rev. B 77, 184418 (2008)] published Thu May 15, 2008.
Magnetic polarization of noble metals by Co nanoparticles in M-capped granular multilayers (M = Cu, Ag, and Au): An x-ray magnetic circular dichroism study
J. Bartolome, L. M. Garcia, F. Bartolome, F. Luis, R. Lopez-Ruiz et al.
X-ray magnetic circular dichroism spectra have been recorded at the L edges of Co, Cu, Ag, and Au, and at the K edges of Co and Cu for a series of multilayer systems of partially self-assembled Co nanoparticles, both capped with alumina and with different metals (Cu, Ag, and Au). The orbital and spi ... [Phys. Rev. B 77, 184420 (2008)] published Thu May 15, 2008.
Surface deformation caused by the Abrikosov vortex lattice
Pavel Lipavsky, Klaus Morawetz, Jan KolaCek, and Ernst Helmut Brandt
In superconductors penetrated by Abrikosov vortices, the magnetic pressure and the inhomogeneous condensate density induce a deformation of the ionic lattice. We calculate how this deformation corrugates the surface of a semi-infinite sample. The effect of the surface dipole is included. ... [Phys. Rev. B 77, 184509 (2008)] published Thu May 15, 2008.
Low-temperature dynamics of magnetic colloids studied by time-resolved small-angle neutron scattering
A. Wiedenmann, U. Keiderling, M. Meissner, D. Wallacher, R. Gahler et al.
The dynamics of ordering and relaxation processes in magnetic colloids has been studied by means of stroboscopic small angle neutron scattering techniques in an oscillating magnetic field. Surfactant stabilized ferrofluids (FFs) of FeO and Co nanoparticles have been investigated as a function of tem ... [Phys. Rev. B 77, 184417 (2008)] published Thu May 15, 2008.
Spin solitons and spin waves in chiral and racemic molecular based ferrimagnets
R. Morgunov, M. V. Kirman, K. Inoue, Y. Tanimoto, J. Kishine et al.
Resonant modes corresponding to a spin-soliton resonance (SSR) and a spin-wave resonance (SWR) have been detected and distinguished in the spectra of the electron spin resonance (ESR) of two-dimensional [Cr(CN)][Mn(S)-pnH-(HO)]HO [green needle (GN)] chiral single crystals and three-dimensional [Mn{( ... [Phys. Rev. B 77, 184419 (2008)] published Thu May 15, 2008.
Anisotropic magnetization and dynamic susceptibility sign change in single-crystal Na[sub 0.85]CoO[sub 2]
Jong-Soo Rhyee, J. B. Peng, C. T. Lin, and S. M. Lee
The dc and ac magnetic susceptibilities of NaCoO single crystals were measured for the different crystal orientations of H||(ab) and H||(c) axis. The dc-magnetic susceptibility for H||(c) direction exhibited the antiferromagnetic transition at T=22 K. The thermal hysteresis between the zero-field-c ... [Phys. Rev. B 77, 205108 (2008)] published Wed May 14, 2008.
Effects of double-Gaussian disorder on the dynamics of the quantum XY chain
Zhen-Bo Xu, Xiang-Mu Kong, and Zhong-Qiang Liu
We investigate the dynamics of the random one-dimensional spin-1/2 quantum isotropic XY model in high-temperature limit by the recurrence relations method. Both the time-dependent transverse autocorrelation function and the corresponding spectral density are calculated for the cases that the exchang ... [Phys. Rev. B 77, 184414 (2008)] published Wed May 14, 2008.
Magnetic behavior of melt-spun gadolinium
P. M. Shand, J. G. Bohnet, J. Goertzen, J. E. Shield, D. Schmitter et al.
Melt-spun Gd is a structurally inhomogeneous system consisting of crystalline grains with an average size of 243 nm that are separated by an amorphous interphase. This system exhibits a depression of T (289.700.01 K) relative to bulk Gd (293 K). The effective critical exponents (beta=0.3890.017, g ... [Phys. Rev. B 77, 184415 (2008)] published Wed May 14, 2008.
Critical dynamics in confined systems with quenched random impurities
H. Chamati and E. Korutcheva
We study the critical dynamics of a system confined to a hypercubic geometry with periodic boundary conditions in the presence of quenched short-range correlated impurities. By using the random T model with purely relaxational dynamics (model A) and the renormalization group method in the vicinity o ... [Phys. Rev. B 77, 184416 (2008)] published Wed May 14, 2008.
Spin polarization of the magnetic spiral in NaCu[sub 2]O[sub 2] as seen by nuclear magnetic resonance spectroscopy
A. A. Gippius, A. S. Moskvin, and S.-L. Drechsler
The incommensurate (IC) spin ordering in quasi-one-dimensional edge-shared cuprate NaCuO has been studied by Na nuclear magnetic resonance spectroscopy in an external magnetic field near 6 T applied along the main crystallographic axes. The NMR line shape evolution above and below T[approximate]12 ... [Phys. Rev. B 77, 180403 (2008)] published Wed May 14, 2008.
Thermodynamics of the quantum Ising model in the two-dimensional kagome lattice
Chyh-Hong Chern and Mitsuaki Tsukamoto
In the classical Ising model on the kagome lattice, there are macroscopically degenerate classical states with exponentially decayed spin correlation. As the singular quantum perturbation is introduced by applying the transverse magnetic field, the quantum ground state remains disordered, dubbed by ... [Phys. Rev. B 77, 172404 (2008)] published Wed May 14, 2008.
Induced triplet pairing in clean s-wave superconductor/ferromagnet layered structures
Klaus Halterman, Oriol T. Valls, and Paul H. Barsic
We study induced triplet pairing correlations in clean ferromagnet/superconductor/ferromagnet heterostructures. The pairing state in the superconductor is the conventional singlet s wave, and the angle alpha between the magnetizations of the two ferromagnetic layers is arbitrary. We use a numerical ... [Phys. Rev. B 77, 174511 (2008)] published Wed May 14, 2008.
Deuteron NMR relaxation, spectra, and evidence for the order-disorder phase transition in (ND[sub 4])[sub 2]PtCl[sub 6]
A. Birczynski, E. E. Ylinen, M. Punkkinen, M. Prager, A. M. Szymocha et al.
Deuteron NMR relaxation and spectra were studied at the resonance frequency of 46 MHz in polycrystalline (ND)PtCl between 3005 K. The relaxation rate maximum near 50 K is about 53% smaller than the calculated maximum related to 120 degrees rotations about the threefold symmetry axes of the ammon ... [J. Chem. Phys. 128, 184510 (2008)] published Wed May 14, 2008.
A structural, magnetic, and M[o-umlaut]ssbauer spectral study of the DyCo[sub 4 - x]Fe[sub x]B compounds, with x = 0--3
Herve Mayot, Olivier Isnard, Fernande Grandjean, and Gary J. Long
The DyCoFeB compounds, with x=0, 1, 1.5, 2, 2.5, and 3, have been investigated by x-ray diffraction, magnetic measurements, and iron-57 Mossbauer spectroscopy. The substitution of cobalt by iron induces both an anisotropic increase in the unit-cell volume and a large increase in the Curie temperatur ... [J. Appl. Phys. 103, 093917 (2008)] published Wed May 14, 2008.
Magnetization process of lotus-type porous metals
H. Onishi, S. K. Hyun, H. Nakajima, S. Mitani, K. Takanashi et al.
Effects of porosity and pore orientation on the magnetization process were studied for lotus-type porous nickel and cobalt. It was confirmed that the saturation magnetization of porous metals varied linearly with the porosity, independent of the pore growth directions. Anisotropic behavior was clear ... [J. Appl. Phys. 103, 093539 (2008)] published Wed May 14, 2008.
Phase Controlled Superconducting Proximity Effect Probed by Tunneling Spectroscopy
H. le Sueur, P. Joyez, H. Pothier, C. Urbina, and D. Esteve
Using a dual-mode STM-AFM microscope operating below 50 mK we measured the local density of states along small normal wires connected at both ends to superconductors with different phases. We observe that a uniform minigap can develop in the whole normal wire and in the superconductors near the inte ... [Phys. Rev. Lett. 100, 197002 (2008)] published Wed May 14, 2008.
Local Ferromagnetic Resonance Imaging with Magnetic Resonance Force Microscopy
Yu. Obukhov, D. V. Pelekhov, J. Kim, P. Banerjee, I. Martin et al.
We report nanoscale scanned probe ferromagnetic resonance force microscopy (FMRFM) imaging of individual ferromagnetic microstructures. This reveals the mechanism for high spatial resolution in FMRFM imaging: the strongly inhomogeneous local magnetic field of the cantilever mounted micromagnetic pro ... [Phys. Rev. Lett. 100, 197601 (2008)] published Wed May 14, 2008.
In-field magnetic force microscope study of dipolar interaction in an ideally ordered Co nanorod array fabricated using nanoimprint lithography
T. Wang, Y. Wang, Y. Fu, T. Hasegawa, T. Washiya et al.
We have performed experimental studies and numerical calculations on the dipolar interaction in an ideally ordered hexagonal nanorod array. The dipolar field in an ordered Co nanorod array was measured using an in-field magnetic force microscope (MFM) with a controlled applied field. The average dip ... [Appl. Phys. Lett. 92, 192504 (2008)] published Tue May 13, 2008.
Giant magnetocaloric effect in the Ising antiferromagnet DySb
W. J. Hu, J. Du, B. Li, Q. Zhang, and Z. D. Zhang
The magnetic phase transitions and the magnetocaloric effect in the Ising antiferromagnet DySb have been studied. A field-induced sign change of the magnetocaloric effect has been observed which is related to a first-order field-induced metamagnetic transition from the antiferromagnetic to the ferro ... [Appl. Phys. Lett. 92, 192505 (2008)] published Tue May 13, 2008.
Room temperature soft ferromagnetism in the nanocrystalline form of YCo[sub 2], A well-known bulk Pauli paramagnet
S. Narayana Jammalamadaka, E. V. Sampathkumaran, V. Satya Narayana Murthy, and G. Markandeyulu
The Laves phase compound YCo is a well-known exchange-enhanced Pauli paramagnet. We report here that, in the nanocrystalline form, this compound interestingly is an itinerant ferromagnet at room temperature with a low coercive field. The magnitude of the saturation moment (about 1[mu] per formula un ... [Appl. Phys. Lett. 92, 192506 (2008)] published Tue May 13, 2008.
Temperature dependence of the interface moments in Co[sub 2]MnSi thin films
N. D. Telling, P. S. Keatley, L. R. Shelford, E. Arenholz, G. van der Laan et al.
X-ray magnetic circular dichroism (XMCD) is utilized to explore the temperature dependence of the interface moments in CoMnSi (CMS) thin films capped with aluminum. By increasing the thickness of the capping layer, we demonstrate enhanced interface sensitivity of the measurements. L2-ordered CMS fil ... [Appl. Phys. Lett. 92, 192503 (2008)] published Tue May 13, 2008.
Fe films grown on GaAs(110) in a two-step process: Improved structural and magnetic properties
L. Winking, M. Wenderoth, J. Homoth, S. Siewers, and R. G. Ulbrich
Fe films of up to 10 ML thickness were grown on cleaved GaAs(110) in a two-step process that associates low-temperature deposition at 130 K with a subsequent annealing to room temperature. Low-energy electron diffraction, scanning tunneling microscopy, and in situ magneto-optical Kerr effect were c ... [Appl. Phys. Lett. 92, 193102 (2008)] published Tue May 13, 2008.
Stoichiometric growth of high Curie temperature heavily alloyed GaMnAs
S. Mack, R. C. Myers, J. T. Heron, A. C. Gossard, and D. D. Awschalom
Heavily alloyed, 100 nm GaMnAs (x>0.1) films are obtained via low-temperature molecular beam epitaxy by utilizing a combinatorial technique which allows systematic control of excess arsenic during growth. Reproducible electronic, magnetic, and structural properties are optimized in a narrow range o ... [Appl. Phys. Lett. 92, 192502 (2008)] published Tue May 13, 2008.
Spin-chain magnetism in Eu-doped Ca[sub 3]Co[sub 2]O[sub 6] and Ca[sub 3]CoRhO[sub 6] investigated by M[o-umlaut]ssbauer spectroscopy
P. L. Paulose, Niharika Mohapatra, and E. V. Sampathkumaran
We report the results of Eu Mossbauer effect and magnetization measurements in the Eu-doped CaCoO and CaCoRhO, which are of great current interest in the fields of spin-chain magnetism and geometrical frustration. We find that there is a pronounced increase in the linewidth of the Mossbauer spectra ... [Phys. Rev. B 77, 172403 (2008)] published Tue May 13, 2008.
Field dependence of magnetic correlations through the polarization flop transition in multiferroic TbMnO[sub 3]: Evidence for a magnetic memory effect
D. Senff, P. Link, N. Aliouane, D. N. Argyriou, and M. Braden
The field-induced multiferroic transition in TbMnO has been studied by neutron scattering. Apart from strong hysteresis, the magnetic transition associated with the flop of electronic polarization exhibits a memory effect: after a field sweep, TbMnO does not exhibit the same phase as that obtained b ... [Phys. Rev. B 77, 174419 (2008)] published Tue May 13, 2008.
Melting of magnetic correlations in charge-orbital ordered La[sub 1/2]Sr[sub 3/2]MnO[sub 4]: Competition of ferromagnetic and antiferromagnetic states
D. Senff, O. Schumann, M. Benomar, M. Kriener, T. Lorenz et al.
The magnetic correlations in the charge and orbital ordered manganite LaSrMnO have been studied by elastic and inelastic neutron scattering techniques. Out of the well-defined charge exchange (CE)-type magnetic structure with the corresponding magnons, a competition between CE-type and ferromagnetic ... [Phys. Rev. B 77, 184413 (2008)] published Tue May 13, 2008.
Correlation effects in the electronic structure of the Mn[sub 4] molecular magnet
D. W. Boukhvalov, L. I. Vergara, V. V. Dobrovitski, M. I. Katsnelson, A. I. Lichtenstein et al.
We present joint theoretical-experimental study of correlation effects in the electronic structure of (pyH)[MnOCl(OAc)]2MeCN molecular magnet (Mn). Describing the many-body effects by cluster dynamical mean-field theory, we find that Mn is predominantly a Hubbard insulator with strong electron corre ... [Phys. Rev. B 77, 180402 (2008)] published Tue May 13, 2008.
Effect of oxygen-doping on Bi[sub 2]Sr[sub 2]Ca[sub 2]Cu[sub 3]O[sub 10 + delta] vortex matter: Crossover from electromagnetic to Josephson interlayer coupling
A. Piriou, Y. Fasano, E. Giannini, and O. Fischer
We study the effect of oxygen-doping on the critical temperature T, the vortex matter phase diagram, and the nature of the coupling mechanism between the Cu-O layers in the three-layer BiSrCaCuO (Bi-2223) compound. Contrary to previous reports, in the overdoped (OD) regime, we do find a variation in ... [Phys. Rev. B 77, 184508 (2008)] published Tue May 13, 2008.
Low temperature tunneling magnetoresistance on (La,Sr)MnO[sub 3]/Co junctions with organic spacer layers
H. Vinzelberg, J. Schumann, D. Elefant, R. B. Gangineni, J. Thomas et al.
This paper concerns with giant magnetoresistance (MR) effects in organic spin valves, which are realized as layered (La,Sr)MnO (LSMO)-based junctions with tris-(8, hydroxyquinoline) aluminum (Alq)-spacer and ferromagnetic top layers. The experimental work was focused on the understanding of the tran ... [J. Appl. Phys. 103, 093720 (2008)] published Tue May 13, 2008.
Magnetism in Gd--W films
Giovana Z. Gadioli, Francisco P. Rouxinol, Rogerio V. Gelamo, Adenilson O. dos Santos, Lisandro P. Cardoso et al.
Vapor condensation techniques are useful to prepare magnetic alloys whose components have low or even negligible equilibrium mutual solubility. In this work, one of these techniquessputteringwas used to obtain GdW alloys whose magnetic properties were investigated as a function of the Gd atomic conc ... [J. Appl. Phys. 103, 093916 (2008)] published Tue May 13, 2008.
Optimal control design of NMR and dynamic nuclear polarization experiments using monotonically convergent algorithms
Ivan I. Maximov, Zdenek Tosner, and Niels Chr. Nielsen
Optimal control theory has recently been introduced to nuclear magnetic resonance (NMR) spectroscopy as a means to systematically design and optimize pulse sequences for liquid- and solid-state applications. This has so far primarily involved numerical optimization using gradient-based methods, whic ... [J. Chem. Phys. 128, 184505 (2008)] published Tue May 13, 2008.
Optimal control design of NMR and dynamic nuclear polarization experiments using monotonically convergent algorithms
Ivan I. Maximov, Zdenek Tosner, and Niels Chr. Nielsen
Optimal control theory has recently been introduced to nuclear magnetic resonance (NMR) spectroscopy as a means to systematically design and optimize pulse sequences for liquid- and solid-state applications. This has so far primarily involved numerical optimization using gradient-based methods, whic ... [J. Chem. Phys. 128, 184505 (2008)] published Tue May 13, 2008.
Theory of Ground State Factorization in Quantum Cooperative Systems
Salvatore M. Giampaolo, Gerardo Adesso, and Fabrizio Illuminati
We introduce a general analytic approach to the study of factorization points and factorized ground states in quantum cooperative systems. The method allows us to determine rigorously the existence, location, and exact form of separable ground states in a large variety of, generally nonexactly solva ... [Phys. Rev. Lett. 100, 197201 (2008)] published Tue May 13, 2008.
Behavior of Ising Spin Glasses in a Magnetic Field
Thomas Jorg, Helmut G. Katzgraber, and Florent Krzakala
We study the existence of a spin-glass phase in a field using Monte Carlo simulations performed along a nontrivial path in the field-temperature plane that must cross any putative de AlmeidaThouless instability line. The method is first tested on the Ising spin glass on a Bethe lattice where the ins ... [Phys. Rev. Lett. 100, 197202 (2008)] published Tue May 13, 2008.
Macroscopic Resonant Tunneling in the Presence of Low Frequency Noise
M. H. S. Amin and Dmitri V. Averin
We develop a theory of macroscopic resonant tunneling of flux in a double-well potential in the presence of realistic flux noise with a significant low-frequency component. The rate of incoherent flux tunneling between the wells exhibits resonant peaks, the shape and position of which reflect qualit ... [Phys. Rev. Lett. 100, 197001 (2008)] published Tue May 13, 2008.
Single-ion and exchange anisotropy effects and multiferroic behavior in high-symmetry tetramer single-molecule magnets
Richard A. Klemm and Dmitri V. Efremov
We study single-ion and exchange anisotropy effects in equal-spin s tetramer single-molecule magnets exhibiting T, D, D, C, C, or S ionic site point group symmetry. We first write the group-invariant quadratic single-ion and symmetric anisotropic exchange Hamiltonians in the appropriate local coordi ... [Phys. Rev. B 77, 184410 (2008)] published Mon May 12, 2008.
Superconductivity in the actinoid-bearing filled skutterudite ThPt[sub 4]Ge[sub 12]
D. Kaczorowski and V. H. Tran
ThPtGe is an actinoid-bearing representative of a recently discovered family of Ge-based skutterudites. Based on magnetization, electrical resistivity, and specific heat data, the compound was characterized as a clean-limit strong-coupling superconductor with T=4.62 K. Moreover, some hints are give ... [Phys. Rev. B 77, 180504 (2008)] published Mon May 12, 2008.
Excitation of coupled oscillations in lateral ferromagnetic heterostructures
Nikolay I. Polushkin
The intensities of spin-wave (magnetostatic) modes in thin ferromagnetic films and laterally confined structures are usually insensitive to their dimensions. We observe a strong dependence of the resonant microwave absorption in periodic heterostructures of closely packed ferromagnetic stripes on th ... [Phys. Rev. B 77, 180401 (2008)] published Mon May 12, 2008.
Crossover in the local density of states of mesoscopic superconductor/normal-metal/superconductor junctions
Alex Levchenko
Andreev levels deplete energy states above the superconductive gap, which leads to the peculiar nonmonotonous crossover in the local density of states of mesoscopic superconductor/normal-metal/superconductor junctions. This effect is especially pronounced in the case when the normal metal bridge len ... [Phys. Rev. B 77, 180503 (2008)] published Mon May 12, 2008.
Twisted magnetization state at the interface of an antiferromagnetically coupled Fe/Si multilayer as probed by specular and off-specular polarized neutron scattering
Amitesh Paul, Matthias Buchmeier, Daniel E. Burgler, Ulrich Rucker, and Claus M. Schneider
We have investigated strongly coupled Fe/Si multilayers by polarized neutron scattering in specular and off-specular modes. By using the specular reflectivity patterns as a function of the applied field, we have extracted the magnetization angles for layers buried in the stack. In order to explore t ... [Phys. Rev. B 77, 184409 (2008)] published Mon May 12, 2008.
Relationship between ferroelectricity and Dzyaloshinskii-Moriya interaction in multiferroics and the effect of bond-bending
C. D. Hu
We studied the microscopic mechanism of multiferroics, in particular, with the spin current model [H. Katsura et al., Phys. Rev. Lett. 95, 057205 (2005)]. Starting from a system with helical spin configuration, we solved for the forms of the electron wave functions and analyzed their characteristics ... [Phys. Rev. B 77, 174418 (2008)] published Mon May 12, 2008.
Normal-state transport in electron-doped La[sub 2 - x]Ce[sub x]CuO[sub 4] thin films in magnetic fields up to 40 Tesla
K. Jin, B. Y. Zhu, B. X. Wu, J. Vanacken, V. V. Moshchalkov et al.
The in-plane normal-state transport properties of electron-doped superconductor (LaCe)CuO (LCCO) thin films with 0.06<=x<=0.17 are studied in magnetic fields up to 40 Tesla. For the whole doping region investigated, the negative magnetoresistivity (n-MR) is found below certain temperatures, with mi ... [Phys. Rev. B 77, 172503 (2008)] published Mon May 12, 2008.
Identifying the odd-frequency pairing state of superconductors by a field-induced Josephson effect
Jacob Linder, Takehito Yokoyama, and Asle Sudbo
Superconducting order parameters that are odd under exchange of time coordinates of the electrons constituting a Cooper pair are potentially of great importance both conceptually and technologically. Recent experiments report that such an odd-frequency superconducting bulk state may be realized in c ... [Phys. Rev. B 77, 174507 (2008)] published Mon May 12, 2008.
Effectively doubling the magnetic field in spin-(1/2)--spin-1, HSQC, HDQC, coupled HSQC, and coupled HDQC in solution NMR
S. Chandra Shekar, Jonathan M. Backer, and Mark E. Girvin
Pulse sequences for spin-(1/2)spin-1 pair heteronuclear single quantum correlation (HSQC), heteronuclear double quantum correlation (HDQC), and coupled-HSQC, and coupled-HDQC NMR spectroscopies are outlined, and experimental realization for a CH pair is demonstrated in solution state. In both the co ... [J. Chem. Phys. 128, 184501 (2008)] published Fri May 9, 2008.
Vacancy-induced magnetism in ZnO thin films and nanowires
Qian Wang, Qiang Sun, Gang Chen, Yoshiyuki Kawazoe, and Puru Jena
Extensive calculations based on density functional theory have been carried out to understand the origin of magnetism in undoped ZnO thin films as found in recent experiments. The observed magnetism is confirmed to be due to Zn, instead of O, vacancy. The main source of the magnetic moment, however, ... [Phys. Rev. B 77, 205411 (2008)] published Fri May 9, 2008.
Magnetism and clustering in Cu doped ZnO
Dan Huang, Yu-Jun Zhao, Di-Hu Chen, and Yuan-Zhi Shao
The influence of defect charge state on the magnetism of Cu doped ZnO as well as the Cu defects clustering have been investigated by the first-principles calculations. We demonstrate that p-type ZnO:Cu could have ferromagnetic (FM) property, but n-type ZnO:Cu would not have local magnetic moment. Fu ... [Appl. Phys. Lett. 92, 182509 (2008)] published Fri May 9, 2008.
Manipulation with Andreev states in spin active mesoscopic Josephson junctions
J. Michelsen, V. S. Shumeiko, and G. Wendin
We investigate manipulation with Andreev bound states in Josephson quantum point contacts with magnetic scattering. The Rabi oscillations in the two-level Andreev subsystems are excited by resonant driving the direction of magnetic moment of the scatterer and by modulating the superconducting phase ... [Phys. Rev. B 77, 184506 (2008)] published Fri May 9, 2008.
Josephson current and multiple Andreev reflections in graphene SNS junctions
Xu Du, Ivan Skachko, and Eva Y. Andrei
The Josephson effect and superconducting proximity effect were observed in superconductor-graphene-superconductor (SGS) Josephson junctions with coherence lengths comparable to the distance between the superconducting leads. By comparing the measured gate dependence of the proximity induced subgap f ... [Phys. Rev. B 77, 184507 (2008)] published Fri May 9, 2008.
The crossover from the vortex glass to the Bose glass in nanostructured YBa[sub 2]Cu[sub 3]O[sub 7 - x] films
Tomoya Horide, Kaname Matsumoto, Paolo Mele, Ataru Ichinose, Ryusuke Kita et al.
The glass-liquid transitions of quantized vortices were studied to understand the vortex behavior in YBaCuO films. We systematically controlled the pinning strength, spatial distribution, and shape of disorders by engineering of nanoinclusions in YBaCuO films. In these disorder systems, we observed ... [Appl. Phys. Lett. 92, 182511 (2008)] published Fri May 9, 2008.
Magnetic behavior of Ni nanoparticles with high disordered atomic structure
W. C. Nunes, E. De Biasi, C. T. Meneses, M. Knobel, H. Winnischofer et al.
This report concerns the magnetic properties of colloidal Ni nanoparticles (NPs) obtained by chemical reduction of Ni(II) salt in an organic solvent. The NPs present a complex and disordered atomic structure, where small clusters of a few Ni atoms appear to coexist within each NP. These NPs exhibit ... [Appl. Phys. Lett. 92, 183113 (2008)] published Fri May 9, 2008.
Crystal and magnetic structures of NdBaCo[sub 2]O[sub 5 + delta] (delta ~ 0.75): A neutron diffraction study
D. D. Khalyavin, O. Prokhnenko, N. Stusser, V. Sikolenko, V. Efimov et al.
The crystal structure and magnetic ordering in NdBaCoO cobaltites have been studied by neutron powder diffraction. A successful refinement of the high temperature paramagnetic patterns for both as-prepared (delta~0.71) and oxidized (delta~0.75) compositions was performed in the Pmmm space group with ... [Phys. Rev. B 77, 174417 (2008)] published Fri May 9, 2008.
Calculation of Chern number spin Hamiltonians for magnetic nano-clusters by DFT methods
T. O. Strandberg, C. M. Canali, and A. H. MacDonald
By combining field-theoretical methods and ab initio calculations, we construct an effective Hamiltonian with a single giant-spin degree of freedom, which is capable of describing the low-energy spin dynamics of ferromagnetic metal nano-clusters consisting of up to a few tens of atoms. In our proced ... [Phys. Rev. B 77, 174416 (2008)] published Fri May 9, 2008.
Preparation and properties of amorphous MgB[sub 2]/MgO superstructures: Model disordered superconductor
W. Siemons, M. A. Steiner, G. Koster, D. H. A. Blank, M. R. Beasley et al.
In this paper, we introduce a unique method for fabricating MgB/MgO multilayers and demonstrate the potential for using them as a new model for disordered superconductors. In this approach, we control the annealing of the MgB to yield an interesting new class of disordered (amorphous) superconductor ... [Phys. Rev. B 77, 174506 (2008)] published Fri May 9, 2008.
Canted stripe phase near the spin reorientation transition in ultrathin magnetic films
J. P. Whitehead, A. B. MacIsaac, and K. De'Bell
Results from computer simulation and numerical studies for the ferromagnetic Heisenberg model on a square lattice are presented. The model includes the exchange and dipolar interactions as well as the magnetic anisotropy. The analysis focuses on the nature of the stripe phase which determines the ph ... [Phys. Rev. B 77, 174415 (2008)] published Fri May 9, 2008.
Anomalous temperature-dependent exchange bias in Fe films deposited on Si substrates with the native oxide layer
Wenhong Wang, Fumiyoshi Takano, Masato Takenaka, Hiro Akinaga, and Hironori Ofuchi
The temperature dependence of the exchange bias has been investigated in Fe films deposited on the Si substrates with the native oxidize layer. A crossover from negative to positive exchange bias has been observed with increasing temperature at 30 K, accompanied with the maximum of the coercivity. T ... [J. Appl. Phys. 103, 093914 (2008)] published Fri May 9, 2008.
Magnetization behavior of ordered and high density Co nanowire arrays with varying aspect ratio
G. Kartopu, O. Yalcin, M. Es-Souni, and A. C. Basaran
Densely packed and ordered cobalt nanowire (NW) arrays with aspect ratios (wire length/diameter) varying between 5 and 250 have been fabricated via electrodeposition into alumina templates. The wire length and diameter were controlled by monitoring the total deposited charge or by adjusting the temp ... [J. Appl. Phys. 103, 093915 (2008)] published Fri May 9, 2008.
Restoration of the Magnetic hc/e-Periodicity in Unconventional Superconductors
Vladimir JuriCic, Igor F. Herbut, and Zlatko Tesanovic
We consider the energy of the filled quasiparticle's Fermi sea of a macroscopic superconducting ring threaded by an hc/2e vortex, when the material of the ring is of an unconventional pairing symmetry. The energy relative to the one for the hc/e vortex configuration is finite, positive, and inversel ... [Phys. Rev. Lett. 100, 187006 (2008)] published Fri May 9, 2008.