Fractional Josephson vortices: oscillating macroscopic spins

Photon-induced band bending changes and subsequent relaxation at the buried insulator/semiconductor interface of BaF₂/Si(001) have been investigated. This is achieved by creating free charge carriers through absorption of a visible pump laser pulse (λ=532 nm, E=2.33 eV) in the silicon, followed by time resolved photoelectron spectroscopy using vacuum-ultraviolet synchrotron radiation (E=18 eV) as a probe of the BaF₂ valence band (VB). Since the excitation takes place in the semiconductor and the probe photoemission signal originates from the BaF₂, the relaxation at the interface has been probed. PACS 41.60.Ap; 33.60.Cv; 79.60.Jv; 73.40.Qv