Electronic structure and magnetic and hyperfine properties of Fe/V sandwiches and interfaces

The electronic, magnetic, and hyperfine properties of 15-atom clusters of Fe/V superstructures are calculated using the first-principles discrete-variational X method (DV-X). The superstructures include a monolayer of Fe sandwiched between two thick V layers, an Fe/V interface, and a single layer of Fe on bulk V. The numbers of V atoms in the first and second shells surrounding the central Fe atom (N and M, respectively) were varied and the trends exhibited by the electronic magnetic moments, hyperfine fields, Hc, isomer shifts, IS, and the electric quadrupole splitting, EQ, were investigated. The results show that the magnetic moment on the central Fe atom does not decrease with increasing N contrary to previous interpretations of experimental results. The dependence of the central atom magnetic moment on M is minor. The magnetic hyperfine field decreases in magnitude with increasing N and almost vanishes when N=8. The 3d partial electronic density of states reflects asymmetry in the bonding between the spin-up and the spin-down states of Fe and V and the asymmetry becomes more pronounced with increasing N. The isomer shift of Fe/V systems relative to -Fe becomes more negative as N increases. A linear correlation of the average Hc and IS is found and its slope determined. It is indicated that this slope could be used to determine, the isomer-shift calibration constant. The electric quadrupole splitting EQ shows no regular trends. A model is proposed to explain the above trends.