Wo-dimensional Magnetic Semiconductor

Two-dimensional ferromagnetic semiconductors have broad application prospects in the field of spintronics devices with low power consumption,small size and high speed,and thus become a research hotspot in the fields of condensed matter physics and materials.However,most of the synthesized two-dimensional semiconductor materials are often not magnetic,which limits their practical applications.Studies have shown that building defects and doping of magnetic elements in two-dimensional semiconductor materials can effectively induce magnetism,but the experiment is complicated and the doping or defects are difficult to control.Therefore,finding new intrinsic two-dimensional magnetic semiconductor materials is very important for the research of spintronics.Two-dimensional transition metal dichalcogenide is a typical direct band gap semiconductor material synthesized experimentally.Taking Mo S₂ as an example,its band gap value is 1.8 e V and has a high light absorption coefficient.It is used in field effect transistors,optoelectronics detectors and optoelectronic devices have broad application prospects.However,it has no magnetism,which limits its development in the field of spintronics.In this article,we use a high-throughput calculation method,based on the Mo S₂ rectangular cell crystal structure(with 2 Mo atoms in the cell),the two different transition metals of the 4 to 6 period and the 3 to 7 subgroups are selected to replace the Mo element in the cell,and then screen out the stable magnetic semiconductor materials.The specific research content is as follows:Two different transition metal elements,which from periods 4 to 6 and subgroups3 to 7,replace the two Mo atoms in the rectangular cell,resulting in a total of 91 double transition metal disulfides.Spin polarization calculations show that 48 of them are magnetic.By comparing the energy of the 4 magnetic configurations(1 ferromagnetic,3 antiferromagnetic),it is found that the ferromagnetic state of the 12 structure has the lowest energy.The calculations of electronic properties show that 3 of the structures are semiconductors and the rest are metals.We further added another 6 antiferromagnetic configurations to verify the correctness of the ferromagnetic ground states of the three semiconductor materials,and finally screened out two ferromagnetic semiconductor materials—VNb S₄ and YMo S₄.The phonon spectrum calculation shows that only VNb S₄ is dynamically stable.Spin electron density calculations show that the magnetism of VNb S₄ is mainly derived from V atoms.Band analysis revealed that it is an indirect band gap semiconductor with a band gap of 0.59 e V.The research results in this paper provide some theoretical data for finding new ferromagnetic semiconductors in double transition metal dichalcogenides.