Interlayer ferromagnetism and insulator-metal transition in element-doped CrI3 thin films

TL;DR

This study uses first-principles calculations to show that doping CrI3 with certain nonmagnetic elements can induce interlayer ferromagnetism and cause an insulator-metal transition, offering new ways to control 2D magnetic properties.

Contribution

It reveals that specific element doping can switch CrI3 from antiferromagnetic to ferromagnetic interlayer coupling and induce phase transitions, which was not demonstrated before.

Findings

O, P, S, As, Se doping induces interlayer ferromagnetism.

Doping concentration above 8.33% enables ferromagnetism.

Insulator-metal transition occurs at doping levels between 2.08% and 8.33%.

Abstract

The exploration of magnetism in two-dimensional layered materials has attracted extensive research interest. For the monoclinic phase CrI3 with interlayer antiferromagnetism, finding a static and robust way of realizing the intrinsic interlayer ferromagnetic coupling is desirable. In this Letter, we study the electronic structure and magnetic properties of the nonmagnetic element (e.g., O, S, Se, N, P, As and C) doped bi- and triple-layer CrI3 systems via first-principles calculations. Our results demonstrate that O, P, S, As, and Se doped CrI3 bilayer can realize interlayer ferromagnetism. Further analysis shows that the interlayer ferromagnetic coupling in the doped few-layer CrI3 is closely related to the formation of localized spin-polarized state. This finding indicates that insulated interlayer ferromagnetism can be realized at high doping concentration (larger than 8.33%). When the doping concentration is less than 8.33%, but larger than 2.08%, an insulator-metal phase transition can occur since the localized spin-polarized states percolate to form contiguous grids in few-layer CrI3.