Ferromagnetism and Rashba Spin–Orbit Coupling in the Two-Dimensional (V,Pt)Se₂ Alloy

Abstract

We report on a two-dimensional (2D) V1–x Pt x Se2 alloy that exhibits ferromagnetic order and Rashba spin–orbit coupling. Although ferromagnetism is absent in 1T-VSe2 because of the competition with the charge density wave phase, we demonstrate theoretically and experimentally that the substitution of vanadium by platinum in VSe2 (10–50%) to form a homogeneous 2D alloy restores ferromagnetic order down to one monolayer of V0.65Pt0.35Se2. Moreover, the presence of platinum atoms gives rise to Rashba spin–orbit coupling in (V,Pt)­Se2, providing an original platform to study the interplay between ferromagnetism and spin–orbit coupling in the 2D limit.

The Magnetic Genome of Two-Dimensional van der Waals Materials

“…, 1T-VSe 2 18 and MnSe 2 , 17 have been also reported being magnetic in some of their crystallographic phases or as a result of doping. 437 Ising-type magnetic ordering has also been demonstrated in phosphorus-based insulating antiferromagnets, e.g. , in FePS 3 .…”

Alloying two-dimensional VSe2 with Pt: From a charge density wave state to a disordered insulator

“…Measurements on the (presumably disordered) 2D VxPt1-xSe2 alloys confirmed the presence of magnetism at low temperature in MBE grown layers down to the monolayer limit [22]. Specifically, a ferromagnetic order sets-in below 10-30 K in the monolayer phase for x=0.35 [22].…”

“…Further ab-initio calculations have indeed shown that monolayers of ordered 1T-VxPt1-xSe2 alloys could be ferromagnetic for 0.1<x<0.5 [22], even when the lattice deformation associated with the CDW state was taken into account. Measurements on the (presumably disordered) 2D VxPt1-xSe2 alloys confirmed the presence of magnetism at low temperature in MBE grown layers down to the monolayer limit [22]. Specifically, a ferromagnetic order sets-in below 10-30 K in the monolayer phase for x=0.35 [22].…”

“…Apart from providing magnetic ions, doping also induces some disorder in the TMD layers; and it is known that a small amount of disorder can reduce significantly the critical temperature for the CDW transition in 2D materials [21]. Based on this result, it has been proposed [22] that doping could depress the temperature at which the CDW order develops in monolayer 1T-VSe2 to sufficiently low values to allow for the establishment of the competitive ferromagnetic state. Further ab-initio calculations have indeed shown that monolayers of ordered 1T-VxPt1-xSe2 alloys could be ferromagnetic for 0.1<x<0.5 [22], even when the lattice deformation associated with the CDW state was taken into account.…”

“…Based on this result, it has been proposed [22] that doping could depress the temperature at which the CDW order develops in monolayer 1T-VSe2 to sufficiently low values to allow for the establishment of the competitive ferromagnetic state. Further ab-initio calculations have indeed shown that monolayers of ordered 1T-VxPt1-xSe2 alloys could be ferromagnetic for 0.1<x<0.5 [22], even when the lattice deformation associated with the CDW state was taken into account. Measurements on the (presumably disordered) 2D VxPt1-xSe2 alloys confirmed the presence of magnetism at low temperature in MBE grown layers down to the monolayer limit [22].…”