Interior and edge magnetization in thin exfoliated CrGeTe3 films

TL;DR

This study uses scanning SQUID-on-tip microscopy to analyze the thickness-dependent magnetic properties of exfoliated CrGeTe3 films, revealing edge magnetism and a critical thickness for ferromagnetism relevant for spintronics.

Contribution

It provides the first detailed thickness-dependent magnetization diagram of CrGeTe3 and uncovers unique edge magnetic phenomena using local magnetic imaging.

Findings

No zero-field magnetic memory above 10 nm thickness

Hard ferromagnetism below 10 nm thickness

Identification of unique edge magnetism in CrGeTe3

Abstract

CrGeTe3 (CGT) is a semiconducting vdW ferromagnet shown to possess magnetism down to a two-layer thick sample. Although CGT is one of the leading candidates for spintronics devices, a comprehensive analysis of CGT thickness dependent magnetization is currently lacking. In this work, we employ scanning SQUID-on-tip (SOT) microscopy to resolve the magnetic properties of exfoliated CGT flakes at 4.2 K. Combining transport measurements of CGT/NbSe2 samples with SOT images, we present the magnetic texture and hysteretic magnetism of CGT, thereby matching the global behavior of CGT to the domain structure extracted from local SOT magnetic imaging. Using this method, we provide a thickness dependent magnetization state diagram of bare CGT films. No zero-field magnetic memory was found for films thicker than 10 nm and hard ferromagnetism was found below that critical thickness. Using scanning SOT microscopy, we identify a unique edge magnetism, contrasting the results attained in the CGT interior.