A Symmetry-Breaking Phase in Two-Dimensional FeTe2 with Ferromagnetism above Room Temperature

Liang Liu; Songsong Chen; Zezhou Lin; Xi Zhang

doi:10.1021/acs.jpclett.0c01911

A Symmetry-Breaking Phase in Two-Dimensional FeTe₂ with Ferromagnetism above Room Temperature

J Phys Chem Lett. 2020 Sep 17;11(18):7893-7900. doi: 10.1021/acs.jpclett.0c01911. Epub 2020 Sep 8.

Authors

Liang Liu^{1

2}, Songsong Chen¹, Zezhou Lin¹, Xi Zhang¹

Affiliations

¹ Institute of Nanosurface Science and Engineering, Guangdong Provincial Key Laboratory of Micro/Nano Optomechatronics Engineering, Shenzhen University, Shenzhen 518060, China.
² Key Laboratory of Optoelectronic Devices and Systems of Ministry of Education and Guangdong Province, College of Optoelectronic Engineering, Shenzhen University, Shenzhen 518060, China.

PMID: 32787292
DOI: 10.1021/acs.jpclett.0c01911

Abstract

Recently, ferromagnetism observed in monolayer two-dimensional (2D) materials has attracted attention due to the promise of its application in next-generation spintronics. Here, we predict a symmetry-breaking phase in 2D FeTe₂ that differs from conventional transition metal ditellurides shows superior stability and room-temperature ferromagnetism. Through density functional theory calculations, we find the exchange interactions in FeTe₂ consist of short-range superexchange and long-range oscillatory exchanges mediated by itinerant electrons. For six nearest neighbors, the exchange constants are calculated to be 50.95, 33.41, 2.70, 11.02, 14.46, and -4.12 meV. Furthermore, the strong relativistic effects on Te²⁺ induce giant out-of-plane exchange anisotropy and open up a significantly large spin wave gap (Δ^SW) of 1.22 meV. All of this leads to robust ferromagnetism with the T_c surpassing 423 K, which is predicted by the renormalization group Monte Carlo method, sufficiently higher than room temperature. Our findings shed light on the promising future of FeTe₂ in 2D magnetic research and spintronic applications.