First-principles Study Of Dilute Magnetic Semiconductors Based On LiZnP And LiBeAs

Diluted magnetic semiconductors have both magnetic and semiconductor properties sothat have been widely used in the field of spin electron.Compared with the traditional group II-V and group III-V diluted magnetic semiconductors,the new group i-ii-v diluted magnetic semiconductors can realize the separation of spin and charge injection mechanism with the solid solubility of magnetic ions is not limited,which provides a new direction for the research of diluted magnetic semiconductors,as well as the possibility for the preparation of materials with Curie temperature higher than room temperature and the study of magnetic source mechanism.In this paper,the first principle plane wave pseudopotential method based on density functional theory is used to calculate and analyze the magnetoelectric properties of V-doped i-ii-v semiconductors liznp and V,Cr,Mn doped i-ii-v semiconductors libeas.?1?We optimized the geometry structures of Li_1±y(Zn_1-xV_x)P?x=0,0.0625;y=0,0.0625?by adopting the first-principles calculation of plane wave ultra-soft pseudo-potential technology based upon the density function theory.Then we calculated the electronic structures,formation energies,semi gold attribute,magnetic and Curie temperature.The result reveal that the separation of spin and charge injection mechanisms may be achieved in Li Zn P semiconductor,and the magnetic and electrical properties of diluted magnetic semiconductor may be regulated respectively by V doping and Li stoichiometry.The spin polarized impurity band introduced by single doping V shows strong semi-metallicity,and sp-d hybridization results in a net magnetic moment of 2.92?_B.And the properties of the system are also influenced by the stoichiometric-number of Li.When Li is vacant,semi-metality and magnetic properties are weakened,but the Curie temperature is the highest.When Li is interstitial,the hybridization is enhanced,the formation energy is the lowest,the conductivity is the strongest,and the magnetic is the largest.?2?The intrinsicLiBeAs is a p-type direct bandgap semiconductor and does not show magnetism.The incorporation of V makes the system an indirect band gap semiconductor,exhibits semi-metallic ferromagnetism,produces sp-d hybridization and makes the system's net magnetic moment 4.2?_B.When Li is insufficient,the semi-m etallicity is enhanced and the structure is most stable.When Li is excessive,the system behaves metallic and the conductivity is enhanced.It shows that the new dilute magnetic semiconductor Li_1±y(Be_1-xV_x)As can realize the regulation of magnetoelectric separation by doping V and changing the stoichiometric number of Li.Comparing the optical properties,it is found that the dielectric function of pureLiBeAs is only the dielectric peakgenerated by the valence band electronic conduction band transition,and the complex refractive index function indicates that the system has very weak absorption strength for low-frequency electromagnetic waves.When V is doped alone,a new dielectric peakappears in the dielectric function,and at the same time,the absorption intensity of low-frequency electromagnetic waves is increased.When Li is insufficient,the new dielectric peak disappears,and the complex refractive index fun ction image is similar to pureLiBeAs.When Li is excessive,the new dielectric peak reappears and the peak becomes larger,the absorption of low-frequency electromagn etic waves is further enhanced,It shows that the optical properties of Li_1±y(Be_1-xV_x)As As system will be affected by V doping and Li stoichiometry.?3?When Cr is doped alone,the system also becomes an indirect band gap semi conductor,showing semi-metallic ferromagnetism,the net magnetic moment is 3.92?_B,the system is more stable,the bond lengths of Li-As bond and Be-As bond both b ecome smaller,and the electron cloud Aggregation in the direction of Cr increases the bonding ability and intensifies the electron transfer.When Li is insufficient,the semi-metallicity is enhanced,the structure is the most stable,the bond length of Cr-As is obviously reduced,and the interaction between electrons becomes stronger.When Li is excessive,the system behaves metallic,the conductivity is enhanced,the int eraction betweenatoms is weakened,the charge density overlap is significantly reduced,and the electron overlap layout reaches aminimum of 0.56.It shows that the ne w dilute magneticsemiconductor Li_1±y(Be_1-xCr_x)As As can realize the separation and control of magneticand electrical properties by doping Cr and changing the stoichio metry of Li.Comparing the optical properties,it is found that when Cr is doped al one,a new dielectric peak appears,and the system's ability to absorb low-frequency electromagnetic waves is improved.When Li is insufficient,the dielectric function image and complex refractive index function are similar to pureLiBeAs,When Li is excessive,the new dielectric peak reappears and the peak value increases,and the change of the complex refractive index function in the low energy region is also more obvious.It shows that the optical properties of the doping system will be affected by Cr doping and Li stoichiometry.?4?The doping of Mn produces spin-polarized impurity bands in the system,showing semi-metallic ferromagnetism.When Li is insufficient,the semi-metallicity is strengthened and the structure is most stable.When Li is excessive,the system appea rsmetallic and the conductivity is enhanced.It shows that Mn-dopedLiBeAs new d ilute magnetic semiconductor can achieve magnetic and electrical separation control by doping Mn and changing Li stoichiometry.By comparing the optical properties,it is found thatthe in-band transitions between different states appear in the impurity ba nds produced by Mn doping,new dielectric peaks appear in the low-energy region of the dielectric function,and the absorption of low-frequency electromagnetic waves by the system is improved.When Li is insufficient,the peak value of the new dielec tric peak increases and the refractive index increases.When Li is excessive,the new dielectric peak reappears and moves to the low energy region.Through analysis,it was found that Li Zn P andLiBeAs can adjust the magnetic properties of the system by incorporating magnetic elements.Although different magnetic elements contribute differently to the magnetic properties of the system,they all improve the magnetic properties,stability,By changing the stoichiometric number of Li to control the electrical properties of the system,change the doping orbit,improve the bonding ability of the chemical bonds in the system,and change the medium of electromagnetic wave propagation,thereby affecting its refractive index.This provides reference significance for further experimental research.