Surface alloying and magnetism of ultrathin Fe films on Pd(001)

Abstract

The atomic structure and the chemical composition of ultrathin (<3 monolayer) Fe films grown on a clean Pd(001) at room temperature are studied by low energy electron diffraction (LEED) I/V (spot intensity versus beam energy) analysis with average t-matrix approximation. We find sizable amount of alloying between Fe film and Pd substrate near the interface, and the alloyed Fe films show large tetragonal distortion. Fully relativistic ab initio band structure calculation is performed to elucidate the stability and the correlation between the surface alloying and the magnetic properties of the alloyed Fe film. We find that the sublayer Fe film below 1 ML Pd capping layer is stable compared with the Fe overlayer, supporting efficient inter-diffusion between Fe and Pd, and that lattice spacing in the alloyed Fe films contract as observed by the LEED I/V analysis. The magnetic moments of Fe are found strongly enhanced, and the induced magnetic moments of Pd are also substantial.