Unconventional unidirectional magnetoresistance in heterostructures of a topological semimetal and a ferromagnet

I. Hsuan Kao; Junyu Tang; Gabriel Calderon Ortiz; Menglin Zhu; Sean Yuan; Rahul Rao; Jiahan Li; James H. Edgar; Jiaqiang Yan; David G. Mandrus; Kenji Watanabe; Takashi Taniguchi; Jinwoo Hwang; Ran Cheng; Jyoti Katoch; Simranjeet Singh

doi:10.1038/s41563-025-02175-0

Unconventional unidirectional magnetoresistance in heterostructures of a topological semimetal and a ferromagnet

I. Hsuan Kao, Junyu Tang, Gabriel Calderon Ortiz, Menglin Zhu, Sean Yuan, Rahul Rao, Jiahan Li, James H. Edgar, Jiaqiang Yan, David G. Mandrus, Kenji Watanabe, Takashi Taniguchi, Jinwoo Hwang, Ran Cheng, Jyoti Katoch, Simranjeet Singh

Correlated Electron Materials

Research output: Contribution to journal › Article › peer-review

1 Scopus citations

Abstract

Unidirectional magnetoresistance (UMR) in a bilayer heterostructure, consisting of a spin-source material and a magnetic layer, refers to a change in the longitudinal resistance on the reversal of magnetization and originates from the interaction of non-equilibrium spin accumulation and magnetization at the interface. Since the spin polarization of an electric-field-induced non-equilibrium spin accumulation in conventional spin-source materials is restricted to be in the film plane, the ensuing UMR can only respond to the in-plane component of magnetization. However, magnets with perpendicular magnetic anisotropy are highly desired for magnetic memory and spin-logic devices, whereas the electrical read-out of perpendicular magnetic anisotropy magnets through UMR is critically missing. Here we report the discovery of an unconventional UMR in the heterostructures of a topological semimetal (WTe₂) and a perpendicular magnetic anisotropy ferromagnetic insulator (Cr₂Ge₂Te₆), which allows to electrically read the up and down magnetic states of the Cr₂Ge₂Te₆ layer through longitudinal resistance measurements.

Original language	English
Pages (from-to)	1049-1057
Number of pages	9
Journal	Nature Materials
Volume	24
Issue number	7
DOIs	https://doi.org/10.1038/s41563-025-02175-0
State	Published - Jul 2025

Funding

S.S. acknowledges financial support from the National Science Foundation (NSF) through grant no. ECCS-2208057; US Office of Naval Research under award no. N00014-23-1-2751; and the Center for Emergent Materials at The Ohio State University, an NSF MRSEC, through award no. DMR-2011876. S.S. also acknowledges financial support from the NSF CAREER Award through grant no. ECCS-2339723. J.K. acknowledges financial support from the US Office of Naval Research under award no. N00014-23-1-2751; the Center for Emergent Materials at The Ohio State University, an NSF MRSEC, through award no. DMR-2011876; and the US Department of Energy, Office of Science, Office of Basic Sciences, through award no. DE-SC0020323. J.K. also acknowledges financial support from the NSF CAREER Award under grant no. DMR-2339309. J.T. and R.C. are supported by the Air Force Office of Scientific Research under grant FA9550-19-1-0307. J.Y. acknowledges support from the US Department of Energy, Office of Science, Basic Energy Sciences, Materials Sciences and Engineering Division. D.G.M. acknowledges support from the Gordon and Betty Moore Foundation’s EPiQS Initiative through grant no. GBMF9069. J.H. acknowledges financial support from the Center for Emergent Materials, an NSF MRSEC, through award no. DMR-2011876. Electron microscopy was performed at the Center for Electron Microscopy and Analysis at The Ohio State University. J.H.E. acknowledges support for the hBN crystal growth from the US Office of Naval Research under award no. N00014-22-1-2582. K.W. and T.T. acknowledge support from the JSPS KAKENHI (grant nos. 21H05233 and 23H02052) and World Premier International Research Center Initiative (WPI), MEXT, Japan. We also thank Ryan Muzzio for his help to prepare the schematic of the WTe crystal structure shown in Fig. . 2

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Kao, I. H., Tang, J., Ortiz, G. C., Zhu, M., Yuan, S., Rao, R., Li, J., Edgar, J. H., Yan, J., Mandrus, D. G., Watanabe, K., Taniguchi, T., Hwang, J., Cheng, R., Katoch, J., & Singh, S. (2025). Unconventional unidirectional magnetoresistance in heterostructures of a topological semimetal and a ferromagnet. Nature Materials, 24(7), 1049-1057. https://doi.org/10.1038/s41563-025-02175-0

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title = "Unconventional unidirectional magnetoresistance in heterostructures of a topological semimetal and a ferromagnet",

abstract = "Unidirectional magnetoresistance (UMR) in a bilayer heterostructure, consisting of a spin-source material and a magnetic layer, refers to a change in the longitudinal resistance on the reversal of magnetization and originates from the interaction of non-equilibrium spin accumulation and magnetization at the interface. Since the spin polarization of an electric-field-induced non-equilibrium spin accumulation in conventional spin-source materials is restricted to be in the film plane, the ensuing UMR can only respond to the in-plane component of magnetization. However, magnets with perpendicular magnetic anisotropy are highly desired for magnetic memory and spin-logic devices, whereas the electrical read-out of perpendicular magnetic anisotropy magnets through UMR is critically missing. Here we report the discovery of an unconventional UMR in the heterostructures of a topological semimetal (WTe2) and a perpendicular magnetic anisotropy ferromagnetic insulator (Cr2Ge2Te6), which allows to electrically read the up and down magnetic states of the Cr2Ge2Te6 layer through longitudinal resistance measurements.",

author = "Kao, \{I. Hsuan\} and Junyu Tang and Ortiz, \{Gabriel Calderon\} and Menglin Zhu and Sean Yuan and Rahul Rao and Jiahan Li and Edgar, \{James H.\} and Jiaqiang Yan and Mandrus, \{David G.\} and Kenji Watanabe and Takashi Taniguchi and Jinwoo Hwang and Ran Cheng and Jyoti Katoch and Simranjeet Singh",

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Kao, IH, Tang, J, Ortiz, GC, Zhu, M, Yuan, S, Rao, R, Li, J, Edgar, JH, Yan, J, Mandrus, DG, Watanabe, K, Taniguchi, T, Hwang, J, Cheng, R, Katoch, J & Singh, S 2025, 'Unconventional unidirectional magnetoresistance in heterostructures of a topological semimetal and a ferromagnet', Nature Materials, vol. 24, no. 7, pp. 1049-1057. https://doi.org/10.1038/s41563-025-02175-0

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T1 - Unconventional unidirectional magnetoresistance in heterostructures of a topological semimetal and a ferromagnet

AU - Kao, I. Hsuan

AU - Tang, Junyu

AU - Ortiz, Gabriel Calderon

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AU - Yuan, Sean

AU - Rao, Rahul

AU - Li, Jiahan

AU - Edgar, James H.

AU - Yan, Jiaqiang

AU - Mandrus, David G.

AU - Watanabe, Kenji

AU - Taniguchi, Takashi

AU - Hwang, Jinwoo

AU - Cheng, Ran

AU - Katoch, Jyoti

AU - Singh, Simranjeet

PY - 2025/7

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N2 - Unidirectional magnetoresistance (UMR) in a bilayer heterostructure, consisting of a spin-source material and a magnetic layer, refers to a change in the longitudinal resistance on the reversal of magnetization and originates from the interaction of non-equilibrium spin accumulation and magnetization at the interface. Since the spin polarization of an electric-field-induced non-equilibrium spin accumulation in conventional spin-source materials is restricted to be in the film plane, the ensuing UMR can only respond to the in-plane component of magnetization. However, magnets with perpendicular magnetic anisotropy are highly desired for magnetic memory and spin-logic devices, whereas the electrical read-out of perpendicular magnetic anisotropy magnets through UMR is critically missing. Here we report the discovery of an unconventional UMR in the heterostructures of a topological semimetal (WTe2) and a perpendicular magnetic anisotropy ferromagnetic insulator (Cr2Ge2Te6), which allows to electrically read the up and down magnetic states of the Cr2Ge2Te6 layer through longitudinal resistance measurements.

AB - Unidirectional magnetoresistance (UMR) in a bilayer heterostructure, consisting of a spin-source material and a magnetic layer, refers to a change in the longitudinal resistance on the reversal of magnetization and originates from the interaction of non-equilibrium spin accumulation and magnetization at the interface. Since the spin polarization of an electric-field-induced non-equilibrium spin accumulation in conventional spin-source materials is restricted to be in the film plane, the ensuing UMR can only respond to the in-plane component of magnetization. However, magnets with perpendicular magnetic anisotropy are highly desired for magnetic memory and spin-logic devices, whereas the electrical read-out of perpendicular magnetic anisotropy magnets through UMR is critically missing. Here we report the discovery of an unconventional UMR in the heterostructures of a topological semimetal (WTe2) and a perpendicular magnetic anisotropy ferromagnetic insulator (Cr2Ge2Te6), which allows to electrically read the up and down magnetic states of the Cr2Ge2Te6 layer through longitudinal resistance measurements.

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Unconventional unidirectional magnetoresistance in heterostructures of a topological semimetal and a ferromagnet

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