Electrical mutual switching in a noncollinear-antiferromagnetic-ferromagnetic heterostructure

Yoon, J.-Y.*; 竹内 祐太朗*; 武智 涼太*; Han, J.*; 内山 友宏*; 山根 結太*; 金井 駿*; 家田 淳一; 大野 英男*; 深見 俊輔*

Nature Communications (Internet), 16, p.1171_1 - 1171_8, 2025/02

https://doi.org/10.1038/s41467-025-56157-6

Spin-orbit torque (SOT) provides a promising mechanism for electrically encoding information in magnetic states. Unlike existing schemes, where the SOT is passively determined by the material and device structures, an active manipulation of the intrinsic SOT polarity would allow for flexibly programmable SOT devices. Achieving this requires electrical control of the current-induced spin polarization of the spin source. Here we demonstrate a proof-of-concept current-programmed SOT device. Using a noncollinear-anti-ferromagnetic/nonmagnetic/ferromagnetic MnSn/Mo/CoFeB hetero-structure at zero magnetic eld, we show current-induced switching in the CoFeB layer due to the spin current polarized by the magnetic structure of the MnSn; by properly tuning the driving current, the spin current from the CoFeB further reverses the magnetic orientation of the MnSn, which determines the polarity of the subsequent switching of the CoFeB. This scheme of mutual switching can be achieved in a spin-valve-like simple protocol because each magnetic layer serves as a reversible spin source and target magnetic electrode. It yields intriguing proof-of-concept functionalities for unconventional logic and neuromorphic computing.

Thermal stability of non-collinear antiferromagnetic MnSn nanodot

佐藤 佑磨*; 竹内 祐太郎*; 山根 結太*; Yoon, J.-Y.*; 金井 駿*; 家田 淳一; 大野 英男*; 深見 俊輔*

Applied Physics Letters, 122(12), p.122404_1 - 122404_5, 2023/03

https://doi.org/10.1063/5.0135709

-MnSn, an antiferromagnet having a non-collinear spin structure in a kagome lattice, has attracted great attention owing to various intriguing properties such as large anomalous Hall effect. Stability of magnetic state against thermal fluctuation, characterized in general by the thermal stability factor , has been well studied in ferromagnetic systems but not for antiferromagnets. Here we study of the antiferromagnetic MnSn nanodots as a function of their diameter . To obtain , we measure the switching probability as a function of pulse-field amplitude and analyze the results based on a model developed by accounting for two and six-fold magnetic anisotropies in the kagome plane. We observe no significant change in down to nm below which it decreases with . The obtained dependence is well explained by a single-domain and nucleation-mediated reversal models. These findings provide a basis to understand the thermal fluctuation and reversal mechanism of antiferromagnets for device application.

Observation of domain structure in non-collinear antiferromagnetic MnSn thin films by magneto-optical Kerr effect

内村 友宏*; Yoon, J.-Y.*; 佐藤 佑磨*; 竹内 祐太郎*; 金井 駿*; 武智 涼太*; 岸 桂輔*; 山根 結太*; DuttaGupta, S.*; 家田 淳一; et al.

Applied Physics Letters, 120(17), p.172405_1 - 172405_5, 2022/04

https://doi.org/10.1063/5.0089355

We perform a hysteresis-loop measurement and domain imaging for -oriented -MnSn thin films using magneto-optical Kerr effect (MOKE) and compare it with the anomalous Hall effect (AHE) measurement. We obtain a large Kerr rotation angle of 10 mdeg., comparable with bulk single-crystal MnSn. The composition dependence of AHE and MOKE shows a similar trend, suggesting the same origin, i.e., the non-vanishing Berry curvature in the momentum space. Magnetic domain observation at the saturated state shows that x dependence of AHE and MOKE is explained by an amount of reversible area that crucially depends on the crystalline structure of the film. Furthermore, in-depth observation of the reversal process reveals that the reversal starts with nucleation of sub-micrometer-scale domains dispersed in the film, followed by a domain expansion, where the domain wall preferentially propagates along the direction. Our study provides a basic understanding of the spatial evolution of the reversal of chiral-spin structure in non-collinear antiferromagnetic thin films.

Correlation of anomalous Hall effect with structural parameters and magnetic ordering in MnSn thin films

Yoon, J.-Y.*; 竹内 祐太郎*; DuttaGupta, S.*; 山根 結太*; 金井 駿*; 家田 淳一; 大野 英男*; 深見 俊輔*

AIP Advances (Internet), 11(6), p.065318_1 - 065318_6, 2021/06

https://doi.org/10.1063/5.0043192

We investigate the relationship between structural parameters, magnetic ordering, and the anomalous Hall effect (AHE) of MnSn () thin films annealed at various temperature . The crystal structure changes with and and at C near the stoichiometric composition () epitaxial single-phase 0-MnSn() is obtained. At room temperature, a larger AHE is obtained when the single-phase epitaxial MnSn with the lattice constant closer to that of bulk is formed. The temperature dependence of the AHE shows different behaviors depending on and can be explained by considering the variation of magnetic ordering. A close inspection into the temperature and composition dependence suggests a variation of magnetic phase transition temperature with composition and/or a possible correlation between the AHE and Fermi level position with respect to the Weyl points. Our comprehensive study would provide the basis for utilizing the unique functionalities of non-collinear antiferromagnetic materials.

電子デバイス、その製造方法及びその使用方法

家田 淳一

竹内 祐太朗*; 深見 俊輔*; 山根 結太*; Yoon J.-Y.*; 陣内 佛霖*; 金井 駿*; 大野 英男*

特願 2021-071582  公開特許公報

【課題】 外部磁場が不要であり、比較的大きな読み出し信号の出力が可能な乱数生成素子、メモリ素子として使用することが可能であり、また、出力/入力周波数の可変性を備えた発振/検波素子としても使用することが可能である電子デバイスを提供することを目的とする。 【解決手段】 本体と、入力端子と、出力端子と、を備え、前記本体は、基板上にスピントルク生成層とノンコリニア反強磁性層がこの順、または逆順の積層方向に積層されて構成されるものであり、前記入力端子は、前記スピントルク生成層の積層面と平行な任意の一方向の両端に配置され、前記ノンコリニア反強磁性層は、前記任意の一方向と前記積層方向が成す平面においてノンコリニアな磁気秩序を有することを特徴とする電子デバイス。

電子デバイス、その製造方法及びその使用方法

家田 淳一

竹内 祐太朗*; 深見 俊輔*; 山根 結太*; Yoon J.-Y.*; 陣内 佛霖*; 金井 駿*; 大野 英男*

特願 202280029040.1  公開特許公報

外部磁場が不要であり、比較的大きな読み出し信号の出力が可能な乱数生成素子、メモリ素子として使用することが可能であり、また、出力/入力周波数の可変性を備えた発振/検波素子としても使用することが可能である電子デバイスを提供することを目的とする。 本体と、入力端子と、出力端子と、を備え、前記本体は、基板上にスピントルク生成層とノンコリニア反強磁性層がこの順、または逆順の積層方向に積層されて構成されるものであり、前記入力端子は、前記スピントルク生成層の積層面と平行な任意の一方向の両端に配置され、前記ノンコリニア反強磁性層は、前記任意の一方向と前記積層方向が成す平面においてノンコリニアな磁気秩序を有することを特徴とする電子デバイス。

Room-temperature flexible manipulation of the quantum-metric structure in a topological chiral antiferromagnet

Han, J.*; 内村 友宏*; 荒木 康史; Yoon, J.-Y.*; 竹内 祐太郎*; 山根 結太*; 金井 駿*; 家田 淳一; 大野 英男*; 深見 俊輔*

no journal, , 

The quantum metric and Berry curvature are two fundamental and distinct factors that describe the geometry of quantum eigenstates. While the role of the Berry curvature in governing various condensed-matter states has been investigated extensively, the quantum metric, which was also predicted to induce topological phenomena of equal importance, has rarely been studied. Recently, a breakthrough has been made in observing the quantum-metric nonlinear transport in a van der Waals magnet, but the effect is limited at cryogenic temperature and is tuned by strong magnetic fields of several teslas. In our study, we demonstrate room-temperature manipulation of the quantum-metric structure of electronic states through its interplay with the interfacial spin texture in a topological chiral antiferromagnet/heavy metal Mn3Sn/Pt heterostructure, which is manifested in a time-reversal-odd second-order Hall effect (ScHE). We show the flexibility of controlling the quantum-metric structure with moderate magnetic fields and verify the quantum-metric origin of the observed ScHE by theoretical modeling. Our results open the possibility of building applicable nonlinear devices by harnessing the quantum-metric structure of electronic states.