Berlin 2012 – wissenschaftliches Programm

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HL: Fachverband Halbleiterphysik

HL 91: Poster Session: Spintronics / Magnetic Semiconductors / Transport

HL 91.9: Poster

Donnerstag, 29. März 2012, 16:00–19:00, Poster D

Ground-state properties of Kondo-lattice from spin dynamics — •Alexander Baral and Hans Christian Schneider — Physics Department, University of Kaiserslautern, 67653 Kaiserslautern, Germany

We present theoretical results on the spin dynamics in a Kondo-Lattice using an equation-of-motion approach for one and two-particle correlation functions. We use a s(p)-d model, which describes the exchange interaction between localized magnetic moments and itinerant electrons, in a parameter range typical of the magnetic semiconductor GaMnAs[1]. We set up dynamical equations for the relevant distributions and (spin) correlation functions, and employ different approximations, i.e., truncations of the equation-of-motion hierarchy, up to the level of scattering between correlations and distributions. To keep the numerics tractable, we employ a virtual-crystal approximation and investigate the properties of this system in one dimension. We obtain information on the correlation function between itinerant and localized spins in the ground state by evolving the dynamical equations starting from an uncorrelated initial state. We find long-range spin correlations at low temperatures, with a Kondo-like maximum of the correlation length at finite temperatures. Further, for very low temperatures, Cooper-pair like correlations between different spins and momenta emerge.

[1] L. Cywinski and L. J. Sham, Phys. Rev. B 76, 045205 (2007)