The disordered local moment approach to the spin-disorder resistivity of metallic ferromagnets

J Kudrnovský,V Drchal,I Turek,K D Belashchenko,J K Glasbrenner,S Khmelevskyi,P Tiberto,C De Julián Fernández,S Tacchi,M Affronte,P Vavassori,M Solzi,G Gubbiotti,F Casoli,F Pratt,C Marquina

doi:10.1051/epjconf/20134012001

Abstract

The spin-disorder resistivity (SDR) of transition metal ferromagnets (Fe, Co, Ni), rare-earth ferro- magnet Gd, and Ni2MnSn Heusler alloy is determined from first principles. We identify the SDR at the Curie temperature with the residual resistivity of the corresponding system evaluated in the framework of the disor- dered local moment (DLM) model which has the zero spin-spin correlation function. The underlying electronic structure is determined in the framework of the tight-binding linear mu! n-tin orbital method which employs the coherent potential approximation (CPA) to describe the DLM state. The DLM fixed-spin moment approach is used in the case when the DLM moment collapses. The electronic structure of hcp-Gd is determined using both the open core and LDA+U approaches. The Kubo-Greenwood approach is used to estimate the resistivity. For bcc-Fe and Ni2MnSn alloy we shall also estimate the temperature-dependent of resistivity below the Curie temperature using a semiempirical approach. Calculations are compared with the supercell Landauer-Buttiker approach developed recently as well as with available experimental data and overall good agreement is obtained.

Highlights

Temperature dependence of the resistivity is one of the basic properties of metallic systems
In fcc-Ni, the disordered local moment (DLM) moment collapses to zero while the moment in a real material is expected to persist due to longitudinal spin fluctuations. [18,19] In this case we employ the fixed-spin moment (FSM) approach [20] and treat the local magnetic moment as an adjustable parameter to recover the experimental value of the spindisorder part of the resistivity (SDR) [9]
We have presented a simple theory of the paramagnetic spin-disorder resistivity based on the disordered local moment model combined with the Kubo-Greenwood linearresponse technique and applied it to magnetic transition metals, to the hcp Gadolinium, and to the Ni2MnSn Heusler alloy

Summary

Introduction

Temperature dependence of the resistivity is one of the basic properties of metallic systems. In ferromagnetic metals there is an additional scattering mechanism due to magnetic fluctuations, which usually reach their maximum close to the Curie temperature (Tc) [1,2]. The latter, spindisorder part of the resistivity (SDR) is the subject of this paper. The saturated magnetic resistivity above Tc corresponds to the limit of vanishing spin-spin correlations. It is often extracted from experiment [7] by extrapolation of the phonon contribution to T = 0 and subtracting the residual resistivity

Methods

Results

Conclusion