Probing Magnetism in Insulating Cr2Ge2Te6 by Induced Anomalous Hall Effect in Pt

TL;DR

This study demonstrates that heterostructures of insulating 2D ferromagnet Cr2Ge2Te6 with Pt can reveal its magnetic properties through induced anomalous Hall effect, enabling electrical probing of magnetism in insulating 2D materials.

Contribution

We show that Pt/Cr2Ge2Te6 heterostructures exhibit detectable AHE signals, providing a new method to investigate magnetism in insulating 2D ferromagnets.

Findings

AHE hysteresis persists up to ~60 K, matching the Curie temperature of CGT.

Magnetic domain formation confirmed by magnetic force microscopy.

Density functional theory suggests induced ferromagnetism in Pt causes AHE.

Abstract

Two-dimensional ferromagnet Cr2Ge2Te6 (CGT) is so resistive below its Curie temperature that probing its magnetism by electrical transport becomes extremely difficult. By forming heterostructures with Pt, however, we observe clear anomalous Hall effect (AHE) in 5 nm thick Pt deposited on thin (< 50 nm) exfoliated flakes of CGT. The AHE hysteresis loops persist to ~ 60 K, which matches well to the Curie temperature of CGT obtained from the bulk magnetization measurements. The slanted AHE loops with a narrow opening indicate magnetic domain formation, which is confirmed by low-temperature magnetic force microscopy (MFM) imaging. These results clearly demonstrate that CGT imprints its magnetization in the AHE signal of the Pt layer. Density functional theory calculations of CGT/Pt heterostructures suggest that the induced ferromagnetism in Pt may be primarily responsible for the observed AHE. Our results establish a powerful way of investigating magnetism in 2D insulating ferromagnets which can potentially work for monolayer devices.