Appearance of Ferromagnetism in Pt(100) Ultrathin Films Originated from Quantum-well States

Quantum-well-induced ferromagnetism in thin films

Passage from spin-polarized surface states to unpolarized quantum well states in topologically nontrivial Sb films.

Topological materials have unusual surface spin properties including a net surface spin current protected by the bulk symmetry properties. When such materials are reduced to thin films, their gapless spin-polarized surface states must connect, by analytic continuation, to bulk-derived quantum-well states, which are spin-unpolarized in centrosymmetric systems. The nature of this passage in a mod...

Quantum-size effects in ultrathin Mg films

Recent experiments on the oxidation of ultrathin Mg films have revealed the existence of a correlation between surface reactivity and quantum-size effects. Using ab initio density-functional calculations, we have investigated the electronic properties of epitaxial Mg 0001 films, 5–17 atomic-layer thick, on a W 110 substrate to clarify the origin of this correlation. We find that the decay lengt...

Oscillatory magnetic anisotropy originating from quantum well states in Fe films.

The magnetic anisotropy of Fe film grown on vicinal Ag(1,1,10) surfaces was studied with the in situ magneto-optic Kerr effect. Below 200 K, strong oscillations of the uniaxial magnetic anisotropy as a function of Fe thickness with a period of 5.7 monolayers are found, which can even cause the easy magnetization axis to oscillate between perpendicular and parallel to the steps. Such novel oscil...

Interfacial protection of topological surface states in ultrathin Sb films.

Spin-polarized gapless surface states in topological insulators form chiral Dirac cones. When such materials are reduced to thin films, the Dirac states on the two faces of the film can overlap and couple by quantum tunneling, resulting in a thickness-dependent insulating gap at the Dirac point. Calculations for a freestanding Sb film with a thickness of four atomic bilayers yield a gap of 36 m...