Observation of giant room-temperature anisotropic magnetoresistance in the topological insulator β-Ag2Te

Wei Ai; Fuyang Chen; Zhaochao Liu; Xixi Yuan; Lei Zhang; Yuyu He; Xinyue Dong; Huixia Fu; Feng Luo; Mingxun Deng; Ruiqiang Wang; Jinxiong Wu

doi:10.1038/s41467-024-45643-y

Observation of giant room-temperature anisotropic magnetoresistance in the topological insulator β-Ag₂Te

Nat Commun. 2024 Feb 10;15(1):1259. doi: 10.1038/s41467-024-45643-y.

Authors

Wei Ai^#¹, Fuyang Chen^#², Zhaochao Liu¹, Xixi Yuan³, Lei Zhang¹, Yuyu He¹, Xinyue Dong¹, Huixia Fu⁴, Feng Luo⁵, Mingxun Deng⁶, Ruiqiang Wang², Jinxiong Wu⁷

Affiliations

¹ Tianjin Key Lab for Rare Earth Materials and Applications, Center for Rare Earth and Inorganic Functional Materials, Smart Sensor Interdisciplinary Science Center, School of Materials Science and Engineering, Nankai University, Tianjin, 300350, China.
² Guangdong Provincial Key Laboratory of Quantum Engineering and Quantum Materials, School of Physics, South China Normal University, Guangzhou, 510006, China.
³ Center of Quantum Materials and Devices & College of Physics, Chongqing University, Chongqing, 401331, China.
⁴ Center of Quantum Materials and Devices & College of Physics, Chongqing University, Chongqing, 401331, China. hxfu@cqu.edu.cn.
⁵ Tianjin Key Lab for Rare Earth Materials and Applications, Center for Rare Earth and Inorganic Functional Materials, Smart Sensor Interdisciplinary Science Center, School of Materials Science and Engineering, Nankai University, Tianjin, 300350, China. feng.luo@nankai.edu.cn.
⁶ Guangdong Provincial Key Laboratory of Quantum Engineering and Quantum Materials, School of Physics, South China Normal University, Guangzhou, 510006, China. dengmingxun@scnu.edu.cn.
⁷ Tianjin Key Lab for Rare Earth Materials and Applications, Center for Rare Earth and Inorganic Functional Materials, Smart Sensor Interdisciplinary Science Center, School of Materials Science and Engineering, Nankai University, Tianjin, 300350, China. jxwu@nankai.edu.cn.

^# Contributed equally.

Abstract

Achieving room-temperature high anisotropic magnetoresistance ratios is highly desirable for magnetic sensors with scaled supply voltages and high sensitivities. However, the ratios in heterojunction-free thin films are currently limited to only a few percent at room temperature. Here, we observe a high anisotropic magnetoresistance ratio of -39% and a giant planar Hall effect (520 μΩ⋅cm) at room temperature under 9 T in β-Ag₂Te crystals grown by chemical vapor deposition. We propose a theoretical model of anisotropic scattering - induced by a Dirac cone tilt and modulated by intrinsic properties of effective mass and sound velocity - as a possible origin. Moreover, small-size angle sensors with a Wheatstone bridge configuration were fabricated using the synthesized β-Ag₂Te crystals. The sensors exhibited high output response (240 mV/V), high angle sensitivity (4.2 mV/V/°) and small angle error (<1°). Our work translates the developments in topological insulators to a broader impact on practical applications such as high-field magnetic and angle sensors.