Switching of magnetism via modifying phase shift of quantum-well states by tailoring the interface electronic structure

Abstract

We demonstrate control of the magnetism of Pd(100) ultrathin films, which show d-electron quantum-well induced ferromagnetism, via modulation of the interface electronic state using density functional calculation. From an analysis based on the phase model, forming the Au/Pd(100) interface induces hybridization of the wave function of d-electron quantum-well states, and modulates the term of the scattering phase shift as a function of the reciprocal lattice point. In contrast, forming the Al interface, which has only s-electrons at the Fermi energy, cannot modify the scattering phase shift. Our finding indicates the possibility of modifying the phase shift by tailoring the interface electronic states using hybridization of the wave function, and this efficiently changes the density of states near the Fermi energy of Pd films, and the switching between paramagnetism and ferromagnetism occurs based on the condition for ferromagnetism (Stoner criterion).

Appearance of ferromagnetism in Pt(100) ultrathin films originated from quantum-well states

“…Here, we note that the scattering phase shifts Φ in Eq. ( 1) depend on the in-plane wave number k x,y [32]. This indicates that the shape of the discretized band dispersion depends on the shape of the function Φ, that is, electronic interaction at the Pt/substrate interface.…”

“…Thus, it is suggested that the phenomenon of oscillation is a universal property of transition metals with d-electrons. In the case of Pd, the dependence of the oscillatory behavior on the film thickness was not only discussed from the viewpoint of magnetometry, but also by considering the crystal growth and theoretical analysis of the band dispersion of d-electrons [31,32]. Consequently, these phenomena have been well explained by the change in D( F ) owing to the formation of the d-electron QW states.…”

“…The surface and interface of the prepared ultrathin film behave as an energy barrier, which restricts the movement of electrons in the perpendicular direction and forms QW states. The electronic state can be described by the wave number k z based on the phase model [32][33][34],…”