Non-quasiparticle states in Co2_2MnSi evidenced through magnetic tunnel junction spectroscopy measurements

We investigate the effects of electronic correlations in the full-Heusler Co$_2$MnSi, by combining a theoretical analysis of the spin-resolved density of states with tunneling-conductance spectroscopy measurements using Co$_2$MnSi as electrode. Both experimental and theoretical results confirm the existence of so-called non-quasiparticle states and their crucial contribution to the finite-temperature spin polarisation in this material.Comment: Repalced Fig. 1. of PRL, 100, 086402 (2008), better k-space resolution for DOS around Fermi energ

Magnetic second harmonic generation at the Co2MnSi/AlO x interface

Copyright © 2008 American Institute of PhysicsWe have studied magnetic second harmonic generation (MSHG) at the Co2MnSi/AlOx interface. The variation of the MSHG intensity was consistent with the nonvanishing components of the nonlinear susceptibility tensor expected for the (001) cubic surface. The difference in the MSHG asymmetry, the MSHG anisotropy, is found to have maximum value at an annealing temperature of 450 °C, for which similar samples have previously been found to show optimum L21 site ordering and maximum tunnel magnetoresistance

Theory of current-driven motion of Skyrmions and spirals in helical magnets

We study theoretically the dynamics of the spin textures, i.e., Skyrmion crystal (SkX) and spiral structure (SS), in two-dimensional helical magnets under external current. By numerically solving the Landau-Lifshitz-Gilbert equation, it is found that (i) the critical current density of the motion is much lower for SkX compared with SS in agreement with the recent experiment, (ii) there is no intrinsic pinning effect for SkX and the deformation of the internal structure of Skyrmion reduces the pinning effect dramatically, (iii) the Bragg intensity of SkX shows strong time-dependence as can be observed by neutron scattering experiment.Comment: 4 pages, 3 figure

Ultrafast optical modification of magnetic anisotropy and stimulated precession in an epitaxial Co2 MnAl thin film

Copyright © 2007 American Institute of PhysicsAn all-optical pump-probe method was used to study magnetization precession in an epitaxial Co2MnAl Heusler alloy thin film. The frequency and amplitude of precession showed a clear fourfold variation as the orientation of the static field was applied in different directions within the plane of the film, revealing that the precession is induced by an ultrafast modification of the magnetocrystalline anisotropy field. The effective fields acting upon the magnetization have been determined and the damping parameter is found to decrease rapidly as the strength of the applied field is increased