| As the miniaturization of electronic devices approaches physical limits,facing the increasing information processing and storage requirements,how to further utilize the spin properties of electrons has become a central issue in current spintronics research.While the DMS(Dilute magnetic semiconductors)'s features of combining microelectronics with spin interactions and using charge and spin degrees of freedom to achieve storage and processing integration make it the leading material for spintronics.The ideal dilute magnetic semiconductor should have a ferromagnetic transition temperature above the room temperature and it can also realize the separation and regulation of spin and charge.In this paper,first of all,through the first-principles calculation method based on density functional theory,Fe-doped Li Zn P,Mn-doped LiBeP and Mn-doped LiCdP are theoretically calculated to study the magnetoelectric properties of each system,and then the Mn-doped LiCdP polycrystalline material was experimentally synthesized,its structure,magnetic and electrical properties were measured and analyzed at the same time.The results show:(1)The doping of Fe produces spin-polarized impurity bands in the system,the density peaks of Fe 3d state and Li2 s state,Zn4 s state and P3 p state overlap at the Fermi level,sp-d orbital hybridization occurs,and the material exhibits metallicity.When Li is vacant,according to Zener theory,it is found that less Li can increase the Curie temperature of the system.When taking Li interstitial,the system behaves as a semi-metallic material with 100% spin polarization.It shows that the magnetic and electrical properties of the doping system can be respectively controlled by the doping of Fe and Li content.(2)The calculation result of Mn-doped LiBeP shows that the system forms a strong covalent bond Mn-P bond after Mn is doped,which affects the charge distribution of the entire system.When Li is insufficient,sp-d orbital hybridization occurs,and the system turns to be semi-metallic.It shows that the properties of the system are affected by the stoichiometric number of Li and the semi-metallicity of thesystem can be enhanced by increasing the doping concentration of the magnetic doping element.(3)Theoretical calculations were performed on Mn-doped LiCdP.It was found that when the Mn-doped concentration is 6.25%,the structure produces spin polarization and the system generates a net magnetic moment.Moreover,the calculation of system of Li deficiency and Li interstitial reveals that both systems exhibits semi-metallic properties,in the case of Li interstitial,the semi-metallic band gap is close to 0.5 e V,it indicates that Mn-doped LiCdP is a good backup material for spintronic devices.(4)Mn-doped LiCdP bulk materials were successfully prepared by high-temperature solid-phase method,the results of XRD measurement show that it has a good single-phase structure,and the lattice constant increases with increasing doping concentration.The tlectrical measurements shows that the resistivity of LiCdP decreases with increasing temperature,but when the Mn doping concentration is 5%,the material still behaves as a semiconductor,and the resistance increases significantly due to the doping of Mn,it shows that the doping of Mn forms a local spin in the system,which is also confirmed by the magnetic measurement,and at T = 300 K,the separation of ZFC and FC curves can be observed,it shows that the Curie temperature of Mn-doped LiCdP is 300 K,and it has a ferromagnetic transition temperature close to room temperature. |
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