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Landau theory of tilting of oxygen octahedra in perovskites
Author(s): A. B. Harris
The list of possible commensurate phases obtained from the parent tetragonal phase of Ruddlesden-Popper (RP) systems, An+1BnC3n+1 for general n due to a single phase transition involving the reorienting of octahedra of C (oxygen) ions is reexamined using a Landau expansion. This expansion allows for...
[Phys. Rev. B 85, 174107] Published Fri May 18, 2012
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Structural and vibrational study of cubic Sb_{2}O_{3} under high pressure
Author(s): A. L. J. Pereira, L. Gracia, D. Santamaría-Pérez, R. Vilaplana, F. J. Manjón, D. Errandonea, M. Nalin, and A. Beltrán
We report an experimental and theoretical study of antimony oxide (Sb2O3) in its cubic phase (senarmontite) under high pressure. X-ray diffraction and Raman scattering measurements up to 18 and 25 GPa, respectively, have been complemented with ab initio total-energy and lattice-dynamics calculations...
[Phys. Rev. B 85, 174108] Published Fri May 18, 2012
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Quantum Griffiths singularities in ferromagnetic metals
Author(s): David Nozadze and Thomas Vojta
We present a theory of the quantum Griffiths phases associated with the ferromagnetic quantum phase transition in disordered metals. For Ising spin symmetry, we study the dynamics of a single rare region within the variational instanton approach. For Heisenberg symmetry, the dynamics of the rare reg...
[Phys. Rev. B 85, 174202] Published Fri May 18, 2012
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Power and linewidth of propagating and localized modes in nanocontact spin-torque oscillators
Author(s): Stefano Bonetti, Vito Puliafito, Giancarlo Consolo, Vasyl S. Tiberkevich, Andrei N. Slavin, and Johan Åkerman
The integrated power and linewidth of a propagating and a self-localized spin-wave mode excited by spin-polarized current in an obliquely magnetized magnetic nanocontact are studied experimentally as functions of the angle ?e between the external bias magnetic field and the nanocontact plane. It is ...
[Phys. Rev. B 85, 174427] Published Fri May 18, 2012
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Ultrafast spin-photon interaction investigated with coherent magneto-optics
Author(s): Hélène Vonesch and Jean-Yves Bigot
We investigate the interaction of femtosecond laser pulses with spins including relativistic corrections. The time-ordered magneto-optical signals corresponding to a pump-probe configuration are calculated in the case of one electron submitted to a magnetic field and evolving in eight levels of the ...
[Phys. Rev. B 85, 180407] Published Fri May 18, 2012
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Observation of magnetic moments at the interface region in magnetic tunnel junctions using depth-resolved x-ray magnetic circular dichroism
Author(s): S. Tsunegi, Y. Sakuraba, K. Amemiya, M. Sakamaki, E. Ozawa, A. Sakuma, K. Takanashi, and Y. Ando
The depth-resolved x-ray magnetic circular dichroism (XMCD) technique was applied to observe the interfacial and inner magnetic moments in CoFe/MgO and Co2MnSi(CMS)/MgO. The magnetic moments of the real interface region (two monolayers from the interface) and the inner layers were separately analyze...
[Phys. Rev. B 85, 180408] Published Fri May 18, 2012
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Large magnetic penetration depth and thermal fluctuations in a superconducting Ca_{10}(Pt_{3}As_{8})[(Fe_{1?x}Pt_{x})_{2}As_{2}]_{5} (x=0.097) single crystal
Author(s): Jeehoon Kim, Filip Ronning, N. Haberkorn, L. Civale, E. Nazaretski, Ni Ni, R. J. Cava, J. D. Thompson, and R. Movshovich
We have measured the temperature dependence of the absolute value of the magnetic penetration depth ?(T) in a Ca10(Pt3As8)[(Fe1?xPtx)2As2]5 (x=0.097) single crystal using a low-temperature magnetic force microscope (MFM). We obtain ?ab(0)?1000 nm via extrapolating the data to T=0. This large ? and p...
[Phys. Rev. B 85, 180504] Published Fri May 18, 2012
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Evidence for s_{±}-wave pairing symmetry in LiFeAs from its low-temperature specific heat
Author(s): Dong-Jin Jang, J. B. Hong, Y. S. Kwon, T. Park, K. Gofryk, F. Ronning, J. D. Thompson, and Yunkyu Bang
We report specific heat capacity measurements on a LiFeAs single crystal at temperatures down to 400 mK and magnetic fields up to 9 T. A small specific heat jump at Tc and finite residual density of states at T=0 K in the superconducting (SC) state indicate that there are strong unitary scatterers t...
[Phys. Rev. B 85, 180505] Published Fri May 18, 2012
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Role of intrinsic disorder in the structural phase transition of magnetoelectric EuTiO_{3}
Author(s): Mattia Allieta, Marco Scavini, Leszek J. Spalek, Valerio Scagnoli, Helen C. Walker, Christos Panagopoulos, Siddharth S. Saxena, Takuro Katsufuji, and Claudio Mazzoli
Up to now, the crystallographic structure of the magnetoelectric perovskite EuTiO3 has been considered to remain cubic down to low temperature. Here we present high-resolution synchrotron x-ray powder-diffraction data showing the existence of a structural phase transition, from cubic Pm-3m to tetrag...
[Phys. Rev. B 85, 184107] Published Fri May 18, 2012
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Observation of cross-shaped anisotropy in spin-resolved small-angle neutron scattering
Author(s): Andreas Michels, Dirk Honecker, Frank Döbrich, Charles D. Dewhurst, Kiyonori Suzuki, and André Heinemann
We report the results of spin-resolved small-angle neutron scattering (SANS) experiments on the two-phase nanocrystalline alloy NANOPERM. At a saturating applied magnetic field of 1.27 T we observe a cross-shaped angular anisotropy in the non-spin-flip SANS cross section ?++. This feature?for this c...
[Phys. Rev. B 85, 184417] Published Fri May 18, 2012
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