New publication from Prof. Kan and Deng’s group in Physical Review Letters

 

Recently, professor Erjun Kan, Kaiming Deng, Haiping Wu and their group from School of Science of our university cooperated with professor Hongjun Xiang from Fudan university, published their new work entitled as “Prediction of intrinsic ferromagnetic ferroelectricity in a transition-metal halide monolayer” in the top scientific journal “Physical Review Letters”. Ph. D student Chengxi Huang is the first author. Physical Review Letters the top journal in the field of condensed matter physics, which is conducted by the American Physical Society.

 

Materials possessing ferroelectricity and ferromagntism are usually called multiferroic or magnetoelectric materials. The coexistence and interaction between ferroelectricity and ferromagntism may lead to multi-functional electroic devices, and allow external magnetic and electric field control of the properties of materials. Thus, multiferroic materials are promising materials for applications such as energy transport, information storage and signal transport. The research of two-dimensional multiferroics has received much attention recent years, which may further reveal the physical origin of multiferrocity and promote their practical applications in future nano-devices. However, up to now, two-dimensional multiferroics have never been observed in experiment and are rarely mentioned theoretically. One of the reasons is the inherent incompatibility between ferroelectricity and ferromagntism, which is more notable in a two-dimensional system.

Professor Kan’s group has previously published many remarkable works in the field of spintronics and multiferroics (Nano Letters, 2015, 15, 8277; J. Phys. Chem. Lett, 2016, 10, 1919; J. Am. Chem. Soc, 2012, 134, 5718; Nano Letters, 2016, 16, 8015). In their current work, they firstly proposed the possibility of breaking the incompatibility between ferroelectricity and ferromagntism and realizing two-dimensional multiferroics theoretically. Tactfully, they chose the two-dimensional transition metal halides as examples. On the basis of first-principles calculations, we demonstrate that when doped by odd number of electrons, the two-dimensional CrBr3 will transform to from a normal magnetic semiconductor to a ferroelectric-ferromagnetic semiconductor. This phase transition is caused by Jahn-Teller distortions, which is highly relevant to the strong electronic correlation and the induced ferroelectricity is guaranteed by the cooperation of charge-order and orbital-order. These findings reveal the mysterious curtain of two-dimensional multiferroics, which will greatly promote the theoretical, experimental and application research of two-dimensional multiferroics.

This work is supported by the NSFC, NSF of Jiangsu province and Fundamental Research Funds for the Central Universities.