Open AccessRoom‐Temperature Nanoseconds Spin Relaxation in WTe 2 and MoTe 2 Thin Films
Author(s) -
Wang Qisheng,
Li Jie,
Besbas Jean,
Hsu ChuangHan,
Cai Kaiming,
Yang Li,
Cheng Shuai,
Wu Yang,
Zhang Wenfeng,
Wang Kaiyou,
Chang TayRong,
Lin Hsin,
Chang Haixin,
Yang Hyunsoo
Publication year - 2018
Publication title -
advanced science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.388
H-Index - 100
ISSN - 2198-3844
DOI - 10.1002/advs.201700912
Subject(s) - condensed matter physics , weyl semimetal , spintronics , spins , materials science , spin polarization , physics , semimetal , band gap , electron , ferromagnetism , quantum mechanics
The Weyl semimetal WTe 2 and MoTe 2 show great potential in generating large spin currents since they possess topologically protected spin‐polarized states and can carry a very large current density. In addition, the intrinsic non‐centrosymmetry of WTe 2 and MoTe 2 endows with a unique property of crystal symmetry‐controlled spin–orbit torques. An important question to be answered for developing spintronic devices is how spins relax in WTe 2 and MoTe 2 . Here, a room‐temperature spin relaxation time of 1.2 ns (0.4 ns) in WTe 2 (MoTe 2 ) thin film using the time‐resolved Kerr rotation (TRKR) is reported. Based on ab initio calculation, a mechanism of long‐lived spin polarization resulting from a large spin splitting around the bottom of the conduction band, low electron–hole recombination rate, and suppression of backscattering required by time‐reversal and lattice symmetry operation is identified. In addition, it is found that the spin polarization is firmly pinned along the strong internal out‐of‐plane magnetic field induced by large spin splitting. This work provides an insight into the physical origin of long‐lived spin polarization in Weyl semimetals, which could be useful to manipulate spins for a long time at room temperature.