作成者： 杜 野（東北大CSIS）

2021年度 提案書 （Web公開用）

研 究 プ ロ ジ ェ ク ト 名 ： Spin transport in transition‐metal‐
dichalcogenide (TMDC)/ferromagnet bilayers
概 要 ： Current‐induced spin‐orbit torques are promising for the efficient control of local
magnetizations in spintronic devices. Recent studies suggest that transition‐metal‐dichalcogenide(TMDC) is not only a good candidate for generating spin‐orbit torques, but also a key ingredient topromote field‐free magnetization switching. However, up to now, the underlying physics for theTMDC‐based magnetic hetero‐structures has remained elusive. Specifically, the mechanism of theTMDC‐based spin‐orbit torques is not clear yet. Here in this proposal, we aim to 1) prepare TMDC‐
based magnetic hetero‐structures and 2) study the origin of current‐induced spin‐orbit torques.

コアメンバー： 新田グループ（Tohoku Univ.）、境グループ（QST）

期待される研究成果：
 High‐quality
TMDC/ferromagnet
bilayers will be prepared upon
proper buffer layers.
 The spin Hall magneto‐resistancewill be studied as an initial probe ofcharge‐spin conversion in the system.
 The
current‐inducedspin‐orbittorques will be examined in such
hetero‐structures to study the origin.

(a)

(b)

PRL 110, 206601 (2013)

Figs. (a) Physical process of magnetoresistance originatingfrom spin Hall effect. (b) Schematic demonstration ofharmonic Hall technique for the spin‐orbit torque study.

2020年度 報告書 （Web公開用）

作成者： 杜 野（東北大CSIS）

研 究 プ ロ ジ ェ ク ト 名 ： Spin transport in transition‐metal‐dichalcogenide (TMDC)/ferromagnet bilayers
概 要 ： The spin transport properties in transition‐metal‐dichalcogenide (TMDC)/ferromagnet
bilayers have received increasing attention in recent years because of novel physics arising from thelocal symmetry breaking. Particularly, the charge‐spin current conversion in TMDC/ferromagnet is apromising topic because of potential applications in MRAM. However, up to now, the physical originof the charge‐spin current conversion has remained elusive. In this work, we aim to prepare TMDC‐based magnetic hetero‐structures and to study the spin‐orbit torques of such hetero‐structures.
研究成果（実施状況）：
1. We have successfully prepared thin TMDC
films on top of graphene buffer layer on asapphire substrate. Both TMDC andgraphene show good crystallinity.
2. We have successfully measured andanalyzed the current‐induced spin‐orbit
torques in ferromagnet (FM)/graphenebilayers by using the in‐plane harmonic
Hall measurements (Fig. 1). The obtained
damping‐like and field‐like torques scalewith applied current (Fig. 2).
3. The current‐induced spin‐orbit torques ingraphene/TMDC/ferromagnet
tri‐layer
samples will be studied in the future.

主要発表論文等：

Fig. 1 Damping-like and field-liketerms of the 2nd harmonic signals.

Fig. 2 Damping-like and field-liketorques in FM/graphene bilayers.

2021年度 報告書 （Web公開用）

作成者： 杜 野 （東北大CSIS）

研 究 プ ロ ジ ェ ク ト 名 ： Spin transport in transition‐metal‐dichalcogenide (TMDC)/ferromagnet bilayers
概要： The current‐induced spin‐orbit torque (SOT) has been demonstrated as anefficient method to control local magnetic moments via electric means. Recently, thetransition‐metal‐dichalcogenide (TMDC) was proposed to be a promising candidate as
the SOT generator. In this proposal, we aim to prepare the TMDC materials upon proper
ferromagnet (FM), and to study the related spin transport properties.
研究成果（実施状況）：
1.
We have prepared the FM single layer andFM/graphene bilayers as an initial step, becausegraphene layer is found to be helpful to promote
the TMDC growth.
2.
Magneto‐transport properties have been studied
for FM and FM/graphene samples (Fig. 1).
Relatively low resistivity below 10 µΩ cm and highintrinsic anomalous Hall conductivity of ~700 Ω‐1
cm‐1 have been obtained as shown in Fig. 1(a) and
1(d), suggesting excellent sample quality.
3.
We have studied the temperature dependent SOTin both FM and FM/graphene samples, the results
are under discussion.
4.
Our current study of spin transport in FM andFM/graphene samples provides a solid backgroundfor the preparation of FM/graphene/TMDC and forthe study of spin transport in such tri‐layers. We
plan to prepare FM/graphene/TMDC tri‐layers andto study the spin transport properties in the future.

主要発表論文等：

(a)

(b)

(c)

(d)

Fig.1 Temperature dependence of (a) longitudinal resistivity, (b) anomalous
Hall resistivity, (c) carrier density and (d) anomalous Hall scaling for FM single
layer and FM/graphene bilayers (FM thickness: 10 nm).