Scaling of Berry-curvature monopole dominated large linear positive magnetoresistance
Shen Zhang, Yibo Wang, Qingqi Zeng, Jianlei Shen, Xinqi Zheng, Jinying Yang, Zhaosheng Wang, Chuanying Xi, Binbin Wang, Min Zhou, Rongjin Huang, Hongxiang Wei, Yuan Yao, Shouguo Wang, S. Parkin, Claudia Felser, Enke Liu, Baogen Shen
Abstract
The linear positive magnetoresistance (LPMR) is a widely observed phenomenon in topological materials, which is promising for potential applications on topological spintronics. However, its mechanism remains ambiguous yet, and the effect is thus uncontrollable. Here, we report a quantitative scaling model that correlates the LPMR with the Berry curvature, based on a ferromagnetic Weyl semimetal CoS 2 that bears the largest LPMR of over 500% at 2 K and 9 T, among known magnetic topological semimetals. In this system, masses of Weyl nodes existing near the Fermi level, revealed by theoretical calculations, serve as Berry-curvature monopoles and low-effective-mass carriers. Based on the Weyl picture, we propose a relation <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline" overflow="scroll"> <mml:mrow> <mml:mtext>MR</mml:mtext> <mml:mo>=</mml:mo> <mml:mfrac> <mml:mi>e</mml:mi> <mml:mi mathvariant="italic">ℏ</mml:mi> </mml:mfrac> <mml:mi>B</mml:mi> <mml:msub> <mml:mrow> <mml:mi mathvariant="bold-italic">Ω</mml:mi> </mml:mrow> <mml:mtext>F</mml:mtext> </mml:msub> </mml:mrow> </mml:math> , with B being the applied magnetic field and <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline" overflow="scroll"> <mml:mrow> <mml:msub> <mml:mrow> <mml:mi mathvariant="bold-italic">Ω</mml:mi> </mml:mrow> <mml:mtext>F</mml:mtext> </mml:msub> </mml:mrow> </mml:math> the average Berry curvature near the Fermi surface, and further introduce temperature factor to both MR/ B slope (MR per unit field) and anomalous Hall conductivity, which establishes the connection between the model and experimental measurements. A clear picture of the linearly slowing down of carriers, i.e., the LPMR effect, is demonstrated under the cooperation of the k -space Berry curvature and real-space magnetic field. Our study not only provides experimental evidence of Berry curvature–induced LPMR but also promotes the common understanding and functional designing of the large Berry-curvature MR in topological Dirac/Weyl systems for magnetic sensing or information storage.