156 results found
Umerski A, Edwards DM, 2017, New calculations of Gilbert damping in ferromagnetic transition metals, 8th Joint European Magnetic Symposia (JEMS), Publisher: IOP PUBLISHING LTD, ISSN: 1742-6588
Calculations of the Gilbert damping parameter alpha for bulk Ni are presentedas a function of the spin-dependent Lorentzian broadening of the one-electron states. TheKambersky formula for alpha is used, correctly restricted to second order in the spin-orbitparameter so that intra band terms are suppressed, and the spin-dependent broadening isdeduced from the recent calculations of electron lifetimes due to electron-phonon scatteringby Carva et al. The calculated value of alpha for Ni at room temperature is in reasonableagreement with experiment.
Edwards DM, 2016, The absence of intraband scattering in a consistent theory of Gilbert damping in pure metallic ferromagnets, Journal of Physics: Condensed Matter, Vol: 28, ISSN: 0953-8984
Damping of magnetization dynamics in a ferromagnetic metal, arising from spin–orbit coupling, is usually characterised by the Gilbert parameter α. Recent calculations of this quantity, using a formula due to Kambersky, find that it is infinite for a perfect crystal owing to an intraband scattering term which is of third order in the spin–orbit parameter ξ. This surprising result conflicts with recent work by Costa and Muniz who study damping numerically by direct calculation of the dynamical transverse susceptibility in the presence of spin–orbit coupling. We resolve this inconsistency by following the approach of Costa and Muniz for a slightly simplified model where it is possible to calculate α analytically. We show that to second order in ξ one retrieves the Kambersky result for α, but to higher order one does not obtain any divergent intraband terms. The present work goes beyond that of Costa and Muniz by pointing out the necessity of including the effect of long-range Coulomb interaction in calculating damping for large ξ. A direct derivation of the Kambersky formula is given which shows clearly the restriction of its validity to second order in ξ so that no intraband scattering terms appear. This restriction has an important effect on the damping over a substantial range of impurity content and temperature. The experimental situation is discussed.
Barati E, Cinal M, Edwards DM, et al., 2015, Angular dependence of Gilbert damping in ferromagnetic metallic systems, Ultrafast Magnetization Conference, Publisher: SPRINGER INT PUBLISHING AG, Pages: 50-+, ISSN: 0930-8989
Edwards DM, 2013, A smooth polaron-molecule crossover in a Fermi system, JOURNAL OF PHYSICS-CONDENSED MATTER, Vol: 25, ISSN: 0953-8984
Barati E, Cinal M, Edwards DM, et al., 2012, Calculation of Gilbert damping in ferromagnetic films, 6th Joint European Magnetic Symposia (JEMS), Publisher: E D P SCIENCES, ISSN: 2100-014X
Edwards DM, Ejima S, Alvermann A, et al., 2010, A Green's function decoupling scheme for the Edwards fermion-boson model, JOURNAL OF PHYSICS-CONDENSED MATTER, Vol: 22, ISSN: 0953-8984
Aziz A, Wessely OP, Ali M, et al., 2009, Nonlinear Giant Magnetoresistance in Dual Spin Valves, PHYSICAL REVIEW LETTERS, Vol: 103, ISSN: 0031-9007
Venezuela P, Muniz RB, Costa AT, et al., 2009, Emergence of local magnetic moments in doped graphene-related materials, PHYSICAL REVIEW B, Vol: 80, ISSN: 1098-0121
Edwards DM, Wessely O, 2009, The quantum-mechanical basis of an extended Landau-Lifshitz-Gilbert equation for a current-carrying ferromagnetic wire, JOURNAL OF PHYSICS-CONDENSED MATTER, Vol: 21, ISSN: 0953-8984
Wellein G, Fehske H, Alvermann A, et al., 2008, Correlation-induced metal insulator transition in a two-channel fermion-boson model, PHYSICAL REVIEW LETTERS, Vol: 101, ISSN: 0031-9007
Wessely O, Edwards DM, Mathon J, 2008, Quantum mechanical theory of current-induced domain wall torques in ferromagnetic materials, PHYSICAL REVIEW B, Vol: 77, ISSN: 1098-0121
Edwards DM, Mathon J, 2007, Theory of spin current in magnetic nanopillars for zero-field microwave generation, JOURNAL OF PHYSICS-CONDENSED MATTER, Vol: 19, ISSN: 0953-8984
Alvermann A, Edwards DM, Fehske H, 2007, Boson-controlled quantum transport, PHYSICAL REVIEW LETTERS, Vol: 98, ISSN: 0031-9007
Edwards DM, Umerski A, 2007, Exchange coupling in magnetic multilayers, Handbook of Magnetism and Advanced Magnetic Materials, Editors: Kronmuller, Parkin, Publisher: Wiley, ISBN: 978-0-470-02217-7
Edwards DM, Katsnelson MI, 2006, High-temperature ferromagnetism of sp electrons in narrow impurity bands: application to CaB6, JOURNAL OF PHYSICS-CONDENSED MATTER, Vol: 18, Pages: 7209-7225, ISSN: 0953-8984
Edwards DM, 2006, A quantum phase transition in a model with boson-controlled hopping, International Conference on Strongly Correlated Electron Systems (SECES 05), Pages: 378-380
A model is introduced in which an electron emits or absorbs a local boson every time it hops between lattice sites. The velocity of coherent electron propagation is governed by a control parameter lambda. which determines the rate of boson decay. It is shown how a quantum phase transition between two Fermi liquids, with different Fermi surfaces, can occur at lambda with non-Fermi liquid behaviour persisting down to temperature T = 0 at the critical point. (c) 2006 Elsevier B.V. All rights reserved.
Edwards DM, Mathon J, 2006, Current-induced switching of magnetization, Nanomagnetism: ultrathin films, multilayers and nanostructures, Editors: Mills, Bland, New York, Publisher: Elsevier, Pages: 273-311, ISBN: 9780444516800
Koller W, Hewson AC, Edwards DM, 2005, Polaronic quasiparticles in a strongly correlated electron band, PHYS REV LETT, Vol: 95, Pages: 256401-1-256401-4, ISSN: 0031-9007
We show that a strongly renormalized band of polaronic quasiparticle excitations is induced at the Fermi level of an interacting many-electron system on increasing the coupling of the electrons to local phonons. We give results for the local density of states at zero temperature both for the electrons and phonons. The polaronic quasiparticles satisfy Luttinger's theorem for all regimes considered, and their dispersion shows a kink similar to that observed experimentally in copper oxides. Our calculations are based on the dynamical mean field theory and the numerical renormalization group for the hole-doped Holstein-Hubbard model and large on-site repulsion.
Edwards DM, Federici F, Mathon J, et al., 2005, Self-consistent theory of current-induced switching of magnetization, PHYSICAL REVIEW B, Vol: 71, ISSN: 2469-9950
Edwards DM, 2003, Giant magnetoresistance and layered magnetic structures, Exotic states in quantum nanostructures, Editors: Sarkar, Dordrecht, Publisher: Kluwer, Pages: 213-263, ISBN: 9781402010309
Edwards DM, 2002, Ferromagnetism and electron-phonon coupling in the manganites, ADVANCES IN PHYSICS, Vol: 51, Pages: 1259-1318, ISSN: 0001-8732
Hohenadler M, Edwards DM, 2002, Spectral properties of the Holstein double-exchange model and application to manganites, JOURNAL OF PHYSICS-CONDENSED MATTER, Vol: 14, Pages: 2547-2560, ISSN: 0953-8984
Cinal M, Umerski A, Edwards DM, et al., 2001, Calculated magneto crystalline anisotropy of decorated and undecorated steps on fcc Co(001), International Symposium on Surface and Interface: Properties of Different Symmetry Crossing 2000, Publisher: ELSEVIER SCIENCE BV, Pages: 744-747, ISSN: 0039-6028
Edwards DM, 2001, Eighth NEC Symposium on fundamental approaches to new material phases: Spin-related quantum transport in mesoscopic systems - summary, MATERIALS SCIENCE AND ENGINEERING B-SOLID STATE MATERIALS FOR ADVANCED TECHNOLOGY, Vol: 84, Pages: 138-141, ISSN: 0921-5107
Green ACM, Edwards DM, 2001, A many-body CPA study of quantum effects in the CMR manganites, International Conference on Magnetism, Publisher: ELSEVIER SCIENCE BV, Pages: 886-888, ISSN: 0304-8853
Mathon J, Umerski A, Villeret M, et al., 2000, Induced magnetization spiral in a nonmagnetic metal sandwiched between two ferromagnets, JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS, Vol: 217, Pages: 188-198, ISSN: 0304-8853
Green ACM, Edwards DM, 2000, CPA susceptibility of the double exchange model, 51st Yamada Conference on Strongly Correlated Electon Systems, Publisher: ELSEVIER SCIENCE BV, Pages: 534-535, ISSN: 0921-4526
Green ACM, Edwards DM, 2000, Magnetic susceptibility of the double exchange model, Journal of Physics - Condensed Matter, Vol: 12
Edwards DM, Green ACM, Kubo K, 1999, Quantum spins in the double exchange model of manganites, International Conference on Strongly Correlated Electron Systems (SCES 98), Publisher: ELSEVIER SCIENCE BV, Pages: 810-811, ISSN: 0921-4526
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