Critical behavior of two-dimensional intrinsically ferromagnetic semiconductor CrI3

TL;DR

This study investigates the critical magnetic behavior of the 2D ferromagnetic semiconductor CrI3, revealing a crossover to 3D-Ising behavior near the Curie temperature due to anisotropy and interlayer coupling.

Contribution

It provides the first detailed analysis of the critical exponents of CrI3, demonstrating a crossover from 2D to 3D magnetic behavior in a 2D ferromagnetic semiconductor.

Findings

CrI3 exhibits 3D-Ising critical behavior near T_C

Critical exponents are b{eta}=0.323, b{b}=0.835, b{b}=3.585

Crossover attributed to uniaxial anisotropy and interlayer coupling

Abstract

CrI3, which belongs to a rare category of two-dimensional (2D) ferromagnetic semiconductors, is of great interest for spintronic device applications. Unlike CrCl3 whose magnetism presents a 2D-Heisenberg behavior, CrI3 exhibits a larger van der Waals gap, smaller cleavage energy, and stronger magnetic anisotropy which could lead to a 3D magnetic characteristic. Hence, we investigate the critical behavior of CrI3 in the vicinity of magnetic transition. We use the modified Arrott plot and Kouvel-Fisher method, and conduct critical isotherm analysis to estimate the critical exponents near the ferromagnetic phase transition. This shows that the magnetism of CrI3 follows the crossover behavior of a 3D-Ising model with mean field type interactions where the critical exponents \b{eta}, {\gamma}, and {\delta} are 0.323, 0.835, and 3.585, respectively, at the Curie temperature of 64 K. We propose the crossover behavior can be attributed to the strong uniaxial anisotropy and inevitable interlayer coupling. Our experiment demonstrates the applicability of crossover behavior to a 2D ferromagnetic semiconductor.