A Theoretical Studies On The Structures And Magnetic Properties Of Fev Alloy Clusters

Due to its special d-shell electronic structure,transition metal clusters exhibit unique physicochemical properties.In particular,ferromagnetic transition metal clusters（Fe,Co,Ni）have drawn much attention from the scientific researchers due to its significantly larger magnetic moments than the corresponding bulk materials.More recently,binary transition metal alloy clusters can modulate their chemical and physical properties by changing their chemical composition and size for a specific purpose,which opening the way to a number of potential application in fields such as high density magnetic recording,catalysis,optics and biomedicine.As a result,aiming at their exotic physicochemical properties,and investigating the electronic structure and magnetism of binary transition metal alloy clusters have become one of the most active research subjects in the area of cluster physics.The main contents are as follows:（1）Structural,electronic and magnetic properties of small Fe_mV_n（m+n≤6）clusters:first principles calculationIn this paper,the structural,electronic and magnetic properties of small Fe_mV_n（m+n≤6）clusters have been investigated systematically within the framework of the generalized gradient approximation density-functional theory.The results indicate that the low lying isomers of Fe_mV_n alloy clusters all present the classical closely packed geometries with different chemical order when m+n>4;the ground state structures prefer to form the Fe-V bonds as much as possible.The binding energy of Fe_mV_n clusters always increases with the successive V substitution.The V atom mono-doped and bi-doped make the magnetism of Fe_n clusters decrease 5 and 7μ_B,respectively.With V atom doping increasing,the magnetism presents an overall decreased tendency.The magnetic order bewteen Fe and V atoms undergos a transition from antiferromagnetic coupling in Fe-rich clusters to the coexistence of antiferromagnetic and ferromagnetic couplings in V-rich clusters,and the atom net charge usually transfer from V to Fe atom in Fe_mV_n alloy clusters.（2）Structures,stability,chemical order,magnetic properties of binary Fe_13-nV_n（n=0-13） clustersUsing the generalized gradient approximation of density functional theory,we have calculated the structures,stability,chemical order and magnetic properties of Fe_13-nV_n（n=0-13）atomic clusters.For the 13 atomic clusters,the most stable structures retained the icosahedral morphology,and the clusters tended to form V-V bonds as much as possible.The mixing energy(E_mix)and the chemical order parameter（s）indicated that the Fe and V atoms tend to separate in the most stable structures of clusters.The average binding energy of the clusters（E_b）,the second-order difference energy（（35）₂）and the HOMO-LUMO energy gap（E_g）were calculated to study the stability of the clusters.The Fe₁₂V cluster was found to be the most stable than the neighboring clusters.With the V atoms doping,the total magnetic moments of Fe_13-nV_n（n=0-13）clusters have an overall decrease tendency.We elucidated the physical origin of the magnetic changes from the aspects of the magnetic coupling,the charge transfer phenomenon bewteen Fe atom and V atom,and the orbits hybridization in the clusters.