Thickness-dependent magnetic order in CrI$_3$ single crystals

TL;DR

This study investigates how reducing the thickness of CrI$_3$ crystals affects their magnetic transition temperatures and critical properties, revealing thickness-independent transition at T* and a field-driven metamagnetic transition.

Contribution

It provides detailed insights into the thickness-dependent magnetic behavior and critical phenomena in CrI$_3$, highlighting the crossover from pinning to depinning of magnetic domain walls.

Findings

Bulk T_c is suppressed from 61 K to 57 K with decreasing thickness.

The satellite transition T* at 45 K remains layer-independent.

A field-driven metamagnetic transition occurs around 20 kOe in thin CrI$_3$.

Abstract

Two-dimensional (2D) materials with intrinsic ferromagnetism provide unique opportunity to engineer new functionalities in nano-spintronics. One such material is CrI$_3$, showing long-range magnetic order in monolayer with the Curie temperature ($T_c$) of 45 K. Here we study detailed evolution of magnetic transition and magnetic critical properties in response to systematic reduction in crystal thickness down to 50 nm. Bulk $T_c$ of 61 K is gradually suppressed to 57 K, however, the satellite transition at $T^*$ = 45 K is observed layer-independent at fixed magnetic field of 1 kOe. The origin of $T^*$ is proposed to be a crossover from pinning to depinning of magnetic domain walls. The reduction of thickness facilitates a field-driven metamagnetic transition around 20 kOe with out-of-plane field, in contrast to the continuous changes with in-plane field. The critical analysis around $T_c$ elucidates the mean-field type interactions in microscale-thick CrI$_3$.