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