New publication from Prof. Kan and Deng’s group in the Journal of American

Chemical Society

 

Recently, cooperating with professor Hongjun Xiang from Fudan University and researcher Bing Huang from CSRC, professor Erjun Kan and Kaiming Deng published their new work entitled “Towards Intrinsic Room-temperature Ferromagnetism in Two-dimensional Semiconductors” in the Journal of American Chemical Society. Their Ph. D student Chengxi Huang is the first author. Professor Erjun Kan is the corresponding author.

Ferromagnetic semiconductors allow us to control the magnetic and transport properties of electronic devices on the basis of spin and charge degree of freedom, which is meaningful for the application of logical devices and information storage technology. The studies of ferromagnetic semiconductors started from the 1950s. The conventional ferromagnetic semiconductors are rarely reported and the early discovered ferromagnetic semiconductors usually show Curie temperature much below the room temperature. Up to now, the room-temperature ferromagnetic semiconductors have not been reported yet. One of the 125 important Science question proposed by Science is that Is it possible to create magnetic semiconductors that work at room temperature?” How to improve the Curie temperature of the ferromagnetic semiconductor up to the room temperature has become an important problem desired to be solved.

 

Professor Kan’s group has previously published many remarkable works in the field of ferromagnetic and ferroelectric semiconductor materials (J. Am. Chem. Soc, 2012, 134, 5718; Nano Letters, 2015, 15, 8277; Nano Letters, 2016, 16, 8015; Phys. Rev. Lett. 2018, 120, 147601). In these works, they theoretically clarified the fundamental mechanism of the appearance of ferromagnetic order under a finite temperature, proposed several physical and chemical approaches to realized long-range magnetic order in metal, half-metal and semiconductors, and studied the coexistence of ferromagnetic and ferroelectric order in a single semiconductor. They have made important contributions to the development of the field of spintronic materials

 

 Based on their previous work, in the current work, they firstly proposed a new method that through constructing alloy transition metal compounds to enhance the ferromagnetic couplings in a semiconductor, and achieve intrinsic ferromagnetic semiconductor materials with Curie temperature up to room temperature. The proposed mechanism break the ordinary recognition that super-exchange interactions usually lead to antiferromagnetism or weak ferromagnetism, which is extension of classic super-exchange theory. They chose the recently reported two-dimensional ferromagnetic material CrI3 (Nature, 2017, 546, 270) and CrGeTe3 (Nature, 2017, 546, 265) as examples. On the basis of first-principles calculations and tight-binding analytical methods, they theoretically demonstrated that the Cr, W alloying can remarkably enhance the ferromagnetic couplings in these systems, and improve their Curie temperature up to room-temperature meanwhile the semiconducting feature is well-preserved. These findings will greatly promote the theoretical, experimental and application research of room-temperature ferromagnetic semiconductors. They expect experimental realizations of their proposals, which is meaningful for the development of semiconductor industry of our country.

This work is supported by the NSFC and independent scientific research fund of NJUST