Dirac-Surface-State Modulated Spin Dynamics in a Ferrimagnetic Insulator at Room Temperature

Chi Tang; Qi Song; Cui-Zu Chang; Yadong Xu; Yuichi Ohnuma; Mamoru Matsuo; Yawen Liu; Wei Yuan; Yunyan Yao; Jagadeesh S. Moodera; Sadamichi Maekawa; Wei Han; Jing Shi

arXiv · 1806.00151

Dirac-Surface-State Modulated Spin Dynamics in a Ferrimagnetic Insulator at Room Temperature

Chi Tang·Qi Song·Cui-Zu Chang·Yadong Xu·Yuichi Ohnuma·Mamoru Matsuo·Yawen Liu·Wei Yuan·Yunyan Yao·Jagadeesh S. Moodera·Sadamichi Maekawa·Wei Han·Jing Shi

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Abstract

This work demonstrates dramatically modified spin dynamics of magnetic insulator (MI) by the spin-momentum locked Dirac surface states of the adjacent topological insulator (TI) which can be harnessed for spintronic applications. As the Bi-concentration x is systematically tuned in 5 nm thick (BixSb1-x)2Te3 TI film, the weight of the surface relative to bulk states peaks at x = 0.32 when the chemical potential approaches the Dirac point. At this concentration, the Gilbert damping constant of the precessing magnetization in 10 nm thick Y3Fe5O12 MI film in the MI/TI heterostructures is enhanced by an order of magnitude, the largest among all concentrations. In addition, the MI acquires additional strong magnetic anisotropy that favors the in-plane orientation with similar Bi-concentration dependence. These extraordinary effects of the Dirac surface states distinguish TI from other materials such as heavy metals in modulating spin dynamics of the neighboring magnetic layer.

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Chi Tang, Qi Song, Cui-Zu Chang, Yadong Xu, Yuichi Ohnuma, Mamoru Matsuo, Yawen Liu, Wei Yuan, Yunyan Yao, Jagadeesh S. Moodera, Sadamichi Maekawa, Wei Han, Jing Shi. 2018-06-01. Dirac-Surface-State Modulated Spin Dynamics in a Ferrimagnetic Insulator at Room Temperature. https://arxiv.org/abs/1806.00151

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