PRB: Magnetism

Determination of spin pumping as a source of linewidth in sputtered Co_{90}Fe_{10}/Pd multilayers by use of broadband ferromagnetic resonance spectroscopy

Justin M. Shaw, Hans T. Nembach, and T. J. Silva — 2012-02-10T10:00:00-05:00

Author(s): Justin M. Shaw, Hans T. Nembach, and T. J. Silva

We performed a systematic study of damping in Co₉₀Fe₁₀/Pd multilayers by use of broadband (1–60 GHz) ferromagnetic resonance (FMR) spectroscopy in the perpendicular geometry. The data were fitted with the conventional Landau-Lifshitz equation in conjunction with an inhomogeneous contribution to line...

[Phys. Rev. B 85, 054412] Published Fri Feb 10, 2012

Phase transitions in spin-orbital models with spin-space anisotropies for iron pnictides: Monte Carlo simulations

Ryan Applegate, Rajiv R. P. Singh, Cheng-Chien Chen, and Thomas P. Devereaux — 2012-02-09T10:00:00-05:00

Author(s): Ryan Applegate, Rajiv R. P. Singh, Cheng-Chien Chen, and Thomas P. Devereaux

The common phase diagrams of superconducting iron pnictides show interesting material specificities in the structural and magnetic phase transitions. In some cases the two transitions are separate and second order, while in others they appear to happen concomitantly as a single first-order transitio...

[Phys. Rev. B 85, 054411] Published Thu Feb 09, 2012

Ground-state phase diagram of the quantum J_{1}−J_{2} model on the honeycomb lattice

Fabio Mezzacapo and Massimo Boninsegni — 2012-02-08T10:00:00-05:00

Author(s): Fabio Mezzacapo and Massimo Boninsegni

We study the ground-state phase diagram of the quantum J₁−J₂ model on the honeycomb lattice by means of an entangled-plaquette variational ansatz. Values of energy and relevant order parameters are computed in the range 0≤J₂/J₁≤1. The system displays classical order for J₂/J₁≲0.2 (Néel) and for J₂/J_...

[Phys. Rev. B 85, 060402] Published Wed Feb 08, 2012

Field-induced phases in UPt_{2}Si_{2}

2012-02-08T10:00:00-05:00

Author(s): D. Schulze Grachtrup, M. Bleckmann, B. Willenberg, S. Süllow, M. Bartkowiak, Y. Skourski, H. Rakoto, I. Sheikin, and J. A. Mydosh

The tetragonal compound UPt₂Si₂ has been characterized as a moderately mass-enhanced system with an antiferromagnetic (AFM) ground state below T_N=32 K. Here, we present an extensive study of the behavior in high magnetic fields. We have performed pulsed field magnetization and static field resistivi...

[Phys. Rev. B 85, 054410] Published Wed Feb 08, 2012

Effects of magnetic field, anisotropy, and biquadratic interactions in type-IIA fcc antiferromagnets studied by linear spin-wave theory

Trinanjan Datta and Dao-Xin Yao — 2012-02-07T10:00:00-05:00

Author(s): Trinanjan Datta and Dao-Xin Yao

We study the spin dynamics in a 3D quantum antiferromagnet on a face-centered-cubic (fcc) lattice. The effects of magnetic field, single-ion anisotropy, and biquadratic interactions are investigated using linear spin-wave theory with spins in a canted basis about the type-IIA fcc antiferromagnetic g...

[Phys. Rev. B 85, 054409] Published Tue Feb 07, 2012

Critical temperature and correlation length of an elastic interaction model for spin-crossover materials

2012-02-07T10:00:00-05:00

Author(s): Taro Nakada, Takashi Mori, Seiji Miyashita, Masamichi Nishino, Synge Todo, William Nicolazzi, and Per Arne Rikvold

It has previously been pointed out that the coexistence of infinite-range and short-range interactions causes a system to have a phase transition of the mean-field universality class, in which the cluster size is finite even at the critical point. In the present paper, we study this property in a mo...

[Phys. Rev. B 85, 054408] Published Tue Feb 07, 2012

First-principles study of structural, magnetic, and electronic properties of small Fe-Rh alloy clusters

Junais Habeeb Mokkath and G. M. Pastor — 2012-02-07T10:00:00-05:00

Author(s): Junais Habeeb Mokkath and G. M. Pastor

The structural, electronic, and magnetic properties of small Fe_mRh_n clusters having N=m+n≤8 atoms are studied in the framework of a generalized-gradient approximation to density-functional theory. For N=m+n≤6, a thorough sampling of all cluster topologies has been performed, while for N=7 and 8, onl...

[Phys. Rev. B 85, 054407] Published Tue Feb 07, 2012

Pronounced first-order metamagnetic transition in the paramagnetic heavy-fermion system CeTiGe

2012-02-06T10:00:00-05:00

Author(s): M. Deppe, S. Lausberg, F. Weickert, M. Brando, Y. Skourski, N. Caroca-Canales, C. Geibel, and F. Steglich

We report on the observation of large, steplike anomalies in the magnetization (ΔM=0.74 μ_B/Ce), in the magnetostriction (Δl/l₀=2.0×10⁻³), and in the magnetoresistance in polycrystals of the paramagnetic heavy-fermion system CeTiGe at a critical magnetic field μ₀H_c≈12 T at low temperatures. The size ...

[Phys. Rev. B 85, 060401] Published Mon Feb 06, 2012

Charge pumping by magnetization dynamics in magnetic and semimagnetic tunnel junctions with interfacial Rashba or bulk extrinsic spin-orbit coupling

Farzad Mahfouzi, Jaroslav Fabian, Naoto Nagaosa, and Branislav K. Nikolić — 2012-02-06T10:00:00-05:00

Author(s): Farzad Mahfouzi, Jaroslav Fabian, Naoto Nagaosa, and Branislav K. Nikolić

We develop a time-dependent nonequilibrium Green function (NEGF) approach to the problem of spin pumping by precessing magnetization in one of the ferromagnetic layers within F|I|F magnetic tunnel junctions (MTJs) or F|I|N semi-MTJs in the presence of intrinsic Rashba spin-orbit coupling (SOC) at th...

[Phys. Rev. B 85, 054406] Published Mon Feb 06, 2012

Asymmetric magnetization reversal in dipolarly coupled spin valve structures with perpendicular magnetic anisotropy

2012-02-03T10:00:00-05:00

Author(s): M. Gottwald, M. Hehn, D. Lacour, T. Hauet, F. Montaigne, S. Mangin, P. Fischer, M.-Y. Im, and A. Berger

Magnetization reversal has been studied in a Co₇₄Tb₂₆/Cu/Co₈₈Tb₁₂ system, which is a perpendicularly magnetized ferrimagnetic bilayer separated by a nonmagnetic layer. The Co₈₈Tb₁₂ (soft) layer (SL) exhibits a switching field much lower than the Co₇₄Tb₂₆ (hard) layer (HL), which enabled us to study ...

[Phys. Rev. B 85, 064403] Published Fri Feb 03, 2012

Ordering process and ferroelectricity in a spinel derived from FeV_{2}O_{4}

Q. Zhang, K. Singh, F. Guillou, C. Simon, Y. Breard, V. Caignaert, and V. Hardy — 2012-02-03T10:00:00-05:00

Author(s): Q. Zhang, K. Singh, F. Guillou, C. Simon, Y. Breard, V. Caignaert, and V. Hardy

The spinel FeV₂O₄ is known to exhibit peculiar physical properties, which is generally ascribed to the unusual presence of two cations showing a pronounced interplay between spin, orbital, and lattice degrees of freedom (Fe²⁺ and V³⁺ on the tetrahedral and octahedral sites, respectively). The presen...

[Phys. Rev. B 85, 054405] Published Fri Feb 03, 2012

Al doping effect on magnetic phase transitions of magnetoelectric hexaferrite Ba_{0.7}Sr_{1.3}Zn_{2}(Fe_{1−x}Al_{x})_{12}O_{22}

2012-02-01T10:00:00-05:00

Author(s): Hun Chang, Hak Bong Lee, Young-Sang Song, Jae-Ho Chung, S. A. Kim, I. H. Oh, M. Reehuis, and J. Schefer

We investigated the effect of Al doping in magnetic properties of the Y-type hexaferrite Ba_0.7Sr_1.3Zn₂(Fe_1−xAl_x)₁₂O₂₂ (0≤x≤0.12), which exhibit field-induced magnetoelectric polarization. We find that Al doping increases the pitch of a spin helix and enhances c-axis magnetization, stabilizing longit...

[Phys. Rev. B 85, 064402] Published Wed Feb 01, 2012

Numerical study of the thermodynamics of clinoatacamite

Ehsan Khatami, Joel S. Helton, and Marcos Rigol — 2012-02-01T10:00:00-05:00

Author(s): Ehsan Khatami, Joel S. Helton, and Marcos Rigol

We study the thermodynamic properties of the clinoatacamite compound, Cu₂(OH)₃Cl, by considering several approximate models. They include the Heisenberg model on (i) the uniform pyrochlore lattice, (ii) a very anisotropic pyrochlore lattice, and (iii) a kagome lattice weakly coupled to spins that si...

[Phys. Rev. B 85, 064401] Published Wed Feb 01, 2012

Entanglement spectra of coupled S=1/2 spin chains in a ladder geometry

Andreas M. Läuchli and John Schliemann — 2012-02-01T10:00:00-05:00

Author(s): Andreas M. Läuchli and John Schliemann

We study the entanglement spectrum of spin-1/2 XXZ ladders both analytically and numerically. Our analytical approach is based on perturbation theory starting either from the limit of strong rung coupling, or from the opposite case of dominant coupling along the legs. In the former case we find to l...

[Phys. Rev. B 85, 054403] Published Wed Feb 01, 2012

Frustrated magnetic vortices in hexagonal lattice of magnetic nanocaps

2012-02-01T10:00:00-05:00

Author(s): M. V. Sapozhnikov, O. L. Ermolaeva, B. G. Gribkov, I. M. Nefedov, I. R. Karetnikova, S. A. Gusev, V. V. Rogov, B. B. Troitskii, and L. V. Khokhlova

Magnetic properties of hexagonal lattices of touching magnetic nanocaps fabricated by Co film deposition on a surface of polymethyl methacrylate colloidal crystals was studied as a function of both period (120–450 nm) and thickness (30–60 nm). Magnetization configurations and hysteresis loops of the...

[Phys. Rev. B 85, 054402] Published Wed Feb 01, 2012

Influence of magnetoelectric coupling on electric field induced magnetization reversal in a composite unstrained multiferroic chain

2012-02-01T10:00:00-05:00

Author(s): Paul P. Horley, Alexander Sukhov, Chenglong Jia, Eduardo Martínez, and Jamal Berakdar

We study theoretically the multiferroic dynamics in a composite one-dimensional system consisting of BaTiO₃ multiferroically coupled to an iron chain. The method treats magnetization and polarization as thermodynamic quantities describable via a combination of the Landau-Lifshits-Gilbert and the Gin...

[Phys. Rev. B 85, 054401] Published Wed Feb 01, 2012

Micromagnetic description of the spin spiral in Fe double-layer stripes on W(110)

S. Meckler, O. Pietzsch, N. Mikuszeit, and R. Wiesendanger — 2012-01-31T10:00:00-05:00

Author(s): S. Meckler, O. Pietzsch, N. Mikuszeit, and R. Wiesendanger

The surface spin spiral in the Fe double layer on W(110) is investigated within the framework of micromagnetic theory. It is shown that the previously suggested restriction to homogeneous spiral profiles and the consideration of the demagnetizing energy within the concept of an effective magnetic an...

[Phys. Rev. B 85, 024420] Published Tue Jan 31, 2012

First-principles studies of complex magnetism in Mn nanostructures on the Fe(001) surface

R. N. Igarashi, A. B. Klautau, R. B. Muniz, B. Sanyal, and H. M. Petrilli — 2012-01-31T10:00:00-05:00

Author(s): R. N. Igarashi, A. B. Klautau, R. B. Muniz, B. Sanyal, and H. M. Petrilli

The magnetic properties of Mn nanostructures on the Fe(001) surface have been studied using the noncollinear first-principles real space–linear muffin-tin orbital–atomic sphere approximation method within density-functional theory. We have considered a variety of nanostructures such as adsorbed wire...

[Phys. Rev. B 85, 014436] Published Tue Jan 31, 2012

Wannier-based calculation of the orbital magnetization in crystals

M. G. Lopez, David Vanderbilt, T. Thonhauser, and Ivo Souza — 2012-01-31T10:00:00-05:00

Author(s): M. G. Lopez, David Vanderbilt, T. Thonhauser, and Ivo Souza

We present a first-principles scheme that allows the orbital magnetization of a magnetic crystal to be evaluated accurately and efficiently even in the presence of complex Fermi surfaces. Starting from an initial electronic-structure calculation with a coarse ab initio k-point mesh, maximally locali...

[Phys. Rev. B 85, 014435] Published Tue Jan 31, 2012

Spin dynamics in the frozen state of the dipolar spin ice material Dy_{2}Ti_{2}O_{7}

2012-01-30T10:00:00-05:00

Author(s): L. R. Yaraskavitch, H. M. Revell, S. Meng, K. A. Ross, H. M. L. Noad, H. A. Dabkowska, B. D. Gaulin, and J. B. Kycia

Low-temperature magnetic ac susceptibility measurements of single-crystal dipolar spin ice Dy₂Ti₂O₇ are presented. The relaxation is found to exhibit thermally activated Arrhenius behavior with an activation energy of 9.79 K (∼9J_eff), which is not consistent with a simple scaling of 6J_eff, as previo...

[Phys. Rev. B 85, 020410] Published Mon Jan 30, 2012

Structural, electronic, and magnetic characteristics of Np_{2}Co_{17}

2012-01-30T10:00:00-05:00

Author(s): I. Halevy, A. Hen, I. Orion, E. Colineau, R. Eloirdi, J.-C. Griveau, P. Gaczyński, F. Wilhelm, A. Rogalev, J.-P. Sanchez, M. L. Winterrose, N. Magnani, A. B. Shick, and R. Caciuffo

A previously unknown neptunium-transition-metal binary compound Np₂Co₁₇ has been synthesized and characterized by means of powder x-ray diffraction, ²³⁷Np Mössbauer spectroscopy, superconducting-quantum-interference-device magnetometry, and x-ray magnetic circular dichroism (XMCD). The compound crys...

[Phys. Rev. B 85, 014434] Published Mon Jan 30, 2012

Universal Néel temperature in three-dimensional quantum antiferromagnets

Songbo Jin and Anders W. Sandvik — 2012-01-27T10:00:00-05:00

Author(s): Songbo Jin and Anders W. Sandvik

We study three-dimensional dimerized S=1/2 Heisenberg antiferromagnets, using quantum Monte Carlo simulations of systems with three different dimerization patterns. We propose a way to relate the Néel temperature T_N to the staggered moment m_s of the ground state. Mean-field arguments suggest T_N∝m_s c...

[Phys. Rev. B 85, 020409] Published Fri Jan 27, 2012

Stochastic form of the Landau-Lifshitz-Bloch equation

2012-01-26T10:00:00-05:00

Author(s): R. F. L. Evans, D. Hinzke, U. Atxitia, U. Nowak, R. W. Chantrell, and O. Chubykalo-Fesenko

The Landau-Lifshitz-Bloch equation is a formulation of dynamic micromagnetics valid at all temperatures, treating both the transverse and longitudinal relaxation components important for high-temperature applications. In this paper we discuss two stochastic forms of the Landau-Lifshitz-Bloch equatio...

[Phys. Rev. B 85, 014433] Published Thu Jan 26, 2012

Surface effects on the magnetic behavior of nanoparticle assemblies

G. Margaris, K. Trohidou, and H. Kachkachi — 2012-01-25T10:00:00-05:00

Author(s): G. Margaris, K. Trohidou, and H. Kachkachi

We study the interplay between intrinsic properties and collective effects in assemblies of magnetic nanoparticles. Analytical expressions for the magnetization are obtained for weak dipolar interactions in dilute assemblies. Our study is based on thermodynamic perturbation theory for the effective ...

[Phys. Rev. B 85, 024419] Published Wed Jan 25, 2012

First-principles study of the electronic structure and magnetism of CaIrO_{3}

Alaska Subedi — 2012-01-25T10:00:00-05:00

Author(s): Alaska Subedi

I study the electronic structure and magnetism of postperovskite CaIrO₃ using first-principles calculations. The density functional calculations within the local density approximation without the combined effect of spin-orbit coupling and on-site Coulomb repulsion show the system to be metallic, whi...

[Phys. Rev. B 85, 020408] Published Wed Jan 25, 2012

Restoration of symmetry in the spectrum of the bilayer Heisenberg antiferromagnet

C. J. Hamer, J. Oitmaa, and Zheng Weihong — 2012-01-25T10:00:00-05:00

Author(s): C. J. Hamer, J. Oitmaa, and Zheng Weihong

The longitudinal mode in the Heisenberg model on a bilayer square lattice is studied using series expansion methods. It is demonstrated numerically that the longitudinal mode becomes degenerate with the magnon modes at the quantum phase transition between Néel and dimerized phases, thus forming a sp...

[Phys. Rev. B 85, 014432] Published Wed Jan 25, 2012

Planar approximation for spin transfer systems with application to tilted polarizer devices

Ya. B. Bazaliy — 2012-01-25T10:00:00-05:00

Author(s): Ya. B. Bazaliy

Planar spin transfer devices with dominating easy-plane anisotropy can be described by an effective one-dimensional equation for the in-plane angle. Such a description provides an intuitive qualitative understanding of the magnetic dynamics. We give a detailed derivation of the effective planar equa...

[Phys. Rev. B 85, 014431] Published Wed Jan 25, 2012

Symmetry and nonstoichiometry as possible origins of ferromagnetism in nanoscale oxides

Takashi Uchino and Toshinobu Yoko — 2012-01-25T10:00:00-05:00

Author(s): Takashi Uchino and Toshinobu Yoko

We show through density functional theory calculations that extended magnetic states can inherently occur in oxides as the size of the crystals is reduced down to the nanometer scale. In nanoscale systems, some crystallographically perfect MgO crystallites paradoxically result in nonstoichiometric c...

[Phys. Rev. B 85, 012407] Published Wed Jan 25, 2012

Finite-size corrections of the entanglement entropy of critical quantum chains

J. C. Xavier and F. C. Alcaraz — 2012-01-24T10:00:00-05:00

Author(s): J. C. Xavier and F. C. Alcaraz

Using the density matrix renormalization group, we calculated the finite-size corrections of the entanglement α-Rényi entropy of a single interval for several critical quantum chains. We considered models with U(1) symmetry such as the spin-1/2 XXZ and spin-1 Fateev-Zamolodchikov models, as well as ...

[Phys. Rev. B 85, 024418] Published Tue Jan 24, 2012

Hysteresis and magnetocaloric effect at the magnetostructural phase transition of Ni-Mn-Ga and Ni-Mn-Co-Sn Heusler alloys

2012-01-24T10:00:00-05:00

Author(s): Vittorio Basso, Carlo P. Sasso, Konstantin P. Skokov, Oliver Gutfleisch, and Vladimir V. Khovaylo

Hysteresis features of the direct and inverse magnetocaloric effect associated with first-order magnetostructural phase transitions in Ni-Mn-X (X = Ga, Sn) Heusler alloys have been disclosed by differential calorimetry measurements performed either under a constant magnetic field, H, or by varying H...

[Phys. Rev. B 85, 014430] Published Tue Jan 24, 2012