Tunable Room-Temperature Ferromagnetism in Two-Dimensional Cr₂Te₃

TLDR

Manipulating magnetism offers prospects for data storage and spintronics, yet dimensional reduction universally lowers the ferromagnetic transition temperature. This work synthesizes 1–2 unit‑cell Cr₂Te₃ and demonstrates that dimensional tuning yields room‑temperature ferromagnetism, providing a new strategy to control ferromagnetism. A theoretical model shows that reconstruction of Cr₂Te₃ induces thickness‑dependent Tc. The authors observed Tc rising from 160 K in thick flakes to 280 K in 6‑UC samples and confirmed spontaneous magnetization at room temperature through magnetization and anomalous Hall effect measurements.

Abstract

The manipulation of magnetism provides a unique opportunity for the development of data storage and spintronic applications. Until now, electrical control, pressure tuning, stacking structure dependence, and nanoscale engineering have been realized. However, as the dimensions are decreased, the decrease of the ferromagnetism phase transition temperature (Tc) is a universal trend in ferromagnets. Here, we make a breakthrough to realize the synthesis of 1 and 2 unit cell (UC) Cr2Te3 and discover a room-temperature ferromagnetism in two-dimensional Cr2Te3. The newly observed Tc increases strongly from 160 K in the thick flake (40.3 nm) to 280 K in 6 UC Cr2Te3 (7.1 nm). The magnetization and anomalous Hall effect measurements provided unambiguous evidence for the existence of spontaneous magnetization at room temperature. The theoretical model revealed that the reconstruction of Cr2Te3 could result in anomalous thickness-dependent Tc. This dimension tuning method opens up a new avenue for manipulation of ferromagnetism.