| In recent years,diluted magnetic semiconductors(DMSs)had received much attention due to the possibility of utilizing in spintronic devices.In the traditional DMSs,the spin and charge were introducted at the same time.The new type of DMSs compounds solved the challenge of the "bundling" effect,which provided a new way for the research of DMSs.In this work,the electronic structures and magnetic properties of a new DMS LiZnN were investigated based on the first-principle calculations with the CASTEP code in Materials Studio software.The effects of different transition metal elements,carriers,doping concentrations and doping positions on magnetic properties were analysised,and the ferromagnetic origin of the Li(Zn,TM)N system was studied.In this paper,the main contents and conclusions were summarized as follows:(1)The electronic structures and magnetic properties of LiZnN-based DMSs by doping different transition metal elements(TM=V,Cr,Mn,Fe,Co and Ni)and the TM/Li-codoped LiZnN systems were discussed.In the TM-doped LiZnN systems,the V,Co and Ni-doped LiZnN systems preferred ferromagnetic(FM)states,while the anti-ferromagnetic(AFM)states were the ground states for Cr,Mn and Fe doped LiZnN systems.The Li interstitial atoms changed the magnetic properties of TM-doped LiZnN systems.In the TM/Li-codoped LiZnN systems,Cr/Li,Fe/Li and Co/Li-codoped LiZnN preferred AFM couplings,while the FM states were more stable in the V/Li,Mn/Li and Ni/Li-codoped LiZnN systems.In both of the TM-doped and TM/Li-codoped systems,the TM atoms hybridized with the N atoms,leading to the ferromagnetism.Compared with the TM-doped LiZnN systems,the structural stabilities of the TM/Li-codoped LiZnN systems were energetically more favorable.(2)The effects of carriers on the magnetism of the Mn-doped LiZnN system were studied.The results indicated that the cations(Al3+,La3+,Cat+,Sr2+,Ba2+,Li+,Na+,K+)preferred to replace the Zn2+ions in the Li(Zn,Mn)N system.The trivalent Al3+and La3+ions were added into the Li(Zn,Mn)N systems forming the n-type semiconductor materials,the(Li,La)(Zn,Mn)N and Li(Zn,Mn,Al)N systems were AFM states,while(Li,Al)(Zn,Mn)N and Li(Zn,Mn,La)N exhibited the FM ground states.The divalent cation Ca2+,Sr2+ nd Ba2+doped Li(Zn,Mn)N systems had AFM structures.And the structural stability of Li(Zn,Mn)N system was enhanced by replacing Zn2+ions with Ca2+ions.When adding Li atoms into the Li(Zn,Mn)N system,the structural stability was increased.For the n-type semiconductor materials,the Li(Zn,Mn)N system with Na interstitial atom exhibited AFM state,while the Li(Zn,Mn)N system with K interstitial atom was the FM state.For the p-type semiconductor materials,the FM state was more stable than the AFM state in the Li(Zn,Mn,Na)N system,and the Li(Zn,Mn,K)N system preferred the AFM state.(3)The electronic structures and magnetic properties of Li(Zn,Mn)N system were changed by doping different concentrations of Li and Mn atoms.The structural stabilities of Li(Zn,Mn)N systems enhanced with increasing the doping concentrations of Li and Mn.For the Li16Zn16-xN16(x=1-8)systems with different Mn doping concentrations,the AFM were more stable.For the Li17(Zn16-xMnx)N16(x=1-8)systems,the magnetic stabilities transfered from AFM to the FM states at the doping concentrations of Li and Mn were 6.25 at.%and 12.50 at.%.(4)The electronic structures and magnetic properties of Mn-doped and Mn/Li-codoped LiZnN systems were studied systematically,and the six Li(Zn,Mn)N configurations with different distance between a pair of Mn atoms were also discussed.The results showed that both Mn-doped and Mn/Li-codoped LiZnN systems displayed magnetic properties,and the Mn-doped LiZnN system had the AFM ground state.Owing to the addition of Li interstitial atoms,the ground state of Mn/Li-codoped LiZnN system changed from AFM to FM state.For the Li(Zn,Mn)N system,N atoms acted as an intermediary to couple the two Mn atoms forming the Mn-N-Mn chain,the electrons exchange interaction resulted in the FM coupling between Mn-Mn atoms. |
PDF Full Text Request