(Fe${}_{1-x}$Ni${}_x$)${}_5$GeTe${}_2$: an antiferromagnetic triangular Ising lattice with itinerant magnetism

Abstract

Based on first-principles calculations, an antiferromagnetic Ising model on a triangular lattice has been proposed to interpret the order of Fe$(1)$-Ge pairs and the formation of $\sqrt{3}$ $\times$ $\sqrt{3}$ superstructures in the Fe${}_5$GeTe${}_2$ (F5GT), as well as to predict the existence of similar superstructures in Ni doped F5GT (Ni-F5GT). Our study suggests that F5GT systems may be considered as a structural realization of the well known antiferromagnetic Ising model on a triangular lattice. Based on the superstructures, a Heisenberg-Landau Hamiltonian, taking into account both Heisenberg interactions and longitudinal spin fluctuations, is implemented to describe magnetism in both F5GT and Ni-F5GT. We unveil that frustrated magnetic interactions associated with Fe(1), tuned by a tiny Ni doping ($x\le 0.2$), is responsible for the experimentally observed enhancement of the $T_c$ to 478 K in Ni-F5GT. Our calculations show that at low doping levels, monolayer Ni-F5GT has almost the same magnetic phase diagram as that of the bulk, which indicates a pervasive beyond room temperature ferromagnetism in this Ni doped two-dimensional system.

References in corpus (4)

• Pervasive beyond room-temperature ferromagnetism in a doped van der Waals magnet: Ni doped Fe${}_5$GeTe${}_2$ with $T_{\text{C}}$ up to 478 K
• Strong magneto-optical and anomalous transport manifestations in two-dimensional van der Waals magnets Fe${}_n$GeTe${}_2$ ($n$ = 3, 4, 5)
• Revealing room temperature ferromagnetism in exfoliated Fe${}_5$GeTe${}_2$ flakes with quantum magnetic imaging
• Tuning the Room Temperature Ferromagnetism in Fe5GeTe2 by Arsenic Substitution

Cited by in corpus (4)

• Magnetic Anisotropy in Two-dimensional van der Waals Magnetic Materials and Their Heterostructures: Importance, Mechanisms, and Opportunities
• Field-induced spin polarization in lightly Cr-substituted layered antiferromagnet NiPS3
• Tuning magnetic anisotropy in Fe${}_5$GeTe${}_2$ monolayer through doping and strain
• Quenching the Non-Collinear Spin Order in High-Tc Layered Ferromagnet Fe5GeTe2