Significantly improved Curie temperature in van der Waals Fe3GaTe2 by Li-ion intercalation

Abstract

Magnetic van der Waals (vdW) layered materials have emerged as a research hotspot in condensed matter physics over the past decade. These materials not only exhibit rich physical properties but also provide promising candidates for next-generation magnetic functional devices. For practical applications, the Curie temperature (TC) is a critical performance metric, as it determines the upper limit of the device operating temperature. To date, only a limited number of vdW magnets have been experimentally reported to possess TC above room temperature. Among them, Fe3GaTe2 (FGaT) stands out with a TC of up to 350 K. A substantial enhancement of its TC via compositional modification would not only broaden the working temperature window but also improve functional stability under ambient conditions. Here, density functional theory calculations are employed to construct a Li-intercalated FGaT lattice model, denoted as Li-FGaT, and to study the magnetism enhancement induced by Li-ion intercalation. Our results predict a significantly improved TC of 770 K for Li-FGaT. It is revealed that the electron doping introduced by Li-ion intercalation not only provides interfacial spin-polarized mediating carriers to strengthen the interlayer ferromagnetic coupling but also induces intralayer electron redistribution to enhance the spin exchanges, leading to elevated TC. Thus, this work provides a testable target for experiments and offers useful insights into the development of high-TC vdW magnets.