Issue 8, 2023

Coexistence of ferromagnetism and charge density waves in monolayer LaBr2

Abstract

Charge density waves (CDWs), a common phenomenon of periodic lattice distortions, often suppress ferromagnetism in two-dimensional (2D) materials, hindering their magnetic applications. Here, we report a novel CDW that generates 2D ferromagnetism instead of suppressing it, through the formation of interstitial anionic electrons as the charge modulation mechanism. Via first-principles calculations and a low-energy effective model, we find that the highly symmetrical monolayer LaBr2 undergoes a 2 × 1 CDW transition to a magnetic semiconducting T′ phase. Concurrently, the delocalized 5d1 electrons of La in LaBr2 redistribute and accumulate within the interstitial space in the T′ phase, forming anionic electrons, also known as 2D electride or electrene. The strongly localized nature of anionic electrons promotes a Mott insulating state and full spin-polarization, while the overlap of their extended tails yields ferromagnetic direct exchange between them. Such transition introduces a new magnetic form of CDWs, offering promising opportunities for exploring novel fundamental physics and advanced spintronics applications.

Graphical abstract: Coexistence of ferromagnetism and charge density waves in monolayer LaBr2

Supplementary files

Article information

Article type
Communication
Submitted
19 Apr. 2023
Accepted
22 Jun. 2023
First published
23 Jun. 2023

Nanoscale Horiz., 2023,8, 1054-1061

Coexistence of ferromagnetism and charge density waves in monolayer LaBr2

J. Zhou, Z. Wang, S. Wang, Y. P. Feng, M. Yang and L. Shen, Nanoscale Horiz., 2023, 8, 1054 DOI: 10.1039/D3NH00150D

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