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Effects of electron-phonon scattering on half-metallicity of Co2MnSi

10th International School and Conference on Physics and Applications of Spin Phenomena inSolid (PASPS10)

2018年8月7日(火)

H. Akai

Abstract

Although the existence of a wide gap in the minority spin channel and its half- metallicity ofL21 Co2MnSi are well established in first-principles calculations, these properties turn outrather fragile under realistic situations such as device structures. It has been pointed out thatchemical disorders and defects easily degrade the half-metallic nature of this material. Thesedegradations are structure oriented and therefore static. This means once a perfect structureis attained, there are no reasons of this kind of degradation of the half-metallicity. However,there still exist dynamical effects, caused mainly by phonons and magnons at finitetemperature. In this paper we discuss the effects of electron-phonon scattering on half-metallicity on the basis of first-principles calculations. The phonons are treated as local andstatic (adiabatic) [1], where correlation of the displacements between neighboring sites as wellas dynamical effects is neglected. Then, the phonons are expressed as random displacementsof atoms from their equilibrium positions. Using the distribution of the atomic displacement, theelectronic structures of the system at finite temperature are calculated by regarding thesystem as a disordered system with randomly distributed atomic positions. This kind ofrandomness can be treated using KKR-CPA code [2]. The results show that even at 300 K,the perfect half-metallicity is lost (Fig.1), showing that the effects of phonons are important atusual operating temperatures of devices. The effects on the GMR will be discussed.[1] S. Kou and H. Akai, Solid State Commun. 276, 1 (2018). [2] H. Akai, http://kkr.issp.u-tokyo.ac.jp


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文部科学省

文部科学省
元素戦略プロジェクト(活動紹介)
NIMS磁石パートナーシップ

元素戦略拠点

触媒・電池元素戦略拠点
触媒・電池元素戦略研究拠点 (京都大学)
東工大元素戦略拠点
東工大元素戦略拠点 (東京工業大学)
構造材料元素戦略研究拠点
構造材料元素戦略研究拠点 (京都大学)
高効率モーター用磁性材料技術研究組合
高効率モーター用 磁性材料技術研究組合