The Magnetic And Electrical Properties Of New Diluted Magnetic Semiconductor Based On ?-?-? Group

Diluted magnetic semiconductors with both magnetic and semiconducting properties have broad application prospects in the field of spintronics.Compared with traditional ?-? and ?-? dilute magnetic semiconductors,?-?-? based new dilute magnetic semiconductors can realize the separation of spin and charge injection mechanism,and the solid solubility of magnetic ions is not limited,which provides a new direction for studying dilute magnetic semiconductors,and also provides materials for preparing Curie temperature above room temperature and studying magnetic source mechanism.In this paper,the electronic structure and optical properties of different concentrations of Mn-doped LiMgN,Ag-Cr co-doped LiZnP and different concentrations of Mn/Cr-doped LiCdAs were studied by using first-principles calculation method.Li_1.04(Cd_1-x-x Mn_x)As and Li_1.04(Cd_1-x-x Cr_x)As were successfully prepared and their magnetoelectric properties were measured.Research indicates:?1?The calculation of different concentrations of Mn-doped LiMgN system shows that Mn doping provides spin to the system,and Li content has an effect on the conductivity of the system.The magnetic and electrical separation of LiMgN system can be controlled and the Curie temperature of the system can be improved.The incorporation of Mn and the change in the contents of Li and Mn are achieved.?2?The theoretical calculation of Ag-Cr co-doped LiZnP system:no net magnetic moment in the system of Ag single doping is not magnetic,and when it is doped with Cr,it exhibits metallic ferromagnetism and forms stronger than Zn-P bond.The Cr—P covalent bond,and when Ag-Cr is co-doped,the system becomes semi-metallic ferromagnetism,which is expected to achieve an ideal dilute magnetic semiconductor.?3?The calculation of different concentrations of Mn/Cr doped LiCdAs system shows that the Mn/Cr doping elements are spin-polarized and generate a net magnetic moment.The separation and regulation of the electrical and magnetic properties of the LiCdAs system can be adjusted by adjusting the Li content.This is achieved by changing the concentration of Mn/Cr.In particular,when the Mn concentration is 0.125,the band gap value of the system is substantially zero,and becomes a band gap-free semimetal;when the concentration of Li is increased,when the Cr concentration is increased to 0.125,the system is also a gapless semimetal,and is formed at this time.Thelowest,themoststablesystem.Thetheoreticalcalculationof Li_1±y(Cd_0.875Mn_0.125)As system is carried out by plane wave super soft pseudopotential method and LSDA+U first-principles calculation method.Compared with LSDA method,the band gap value is increased.The system band gap can be opened by the+U method.?4?Measurement of magnetoelectric properties of LiCdAs,Li_1.04(Cd_1-xMn_x)As and Li_1.04(Cd_1-xCr_x)As:It is found that the doping of Mn and Cr can form a local magnetic moment,Mn doping system At low temperature?about 70 K?,the ferrimagnetic state changes to a ferromagnetic state,and at high temperature?about 370 K?,the Curie temperature is measured.At this time,the system changes from a ferromagnetic state to a paramagnetic state,and these magnetic states The phase transition temperature varies with the doping concentration;the Cr doping system measures the Curie temperature at low temperatures,which means that adjusting the doping element and doping amount can obtain an ideal dilute magnetic semiconductor.