Author:
Miyazaki Hidetoshi,Hajiri Tetsuya,Matsunami Masaharu,Inukai Manabu,Ito Takahiro,Kimura Shin-ichi
Abstract
The electronic structure of single-crystalline EuO (100) ultrathin films, together with their exchange splitting energy (ΔEEX) and ferromagnetic phase transition temperature (TC), was investigated by temperature- and thickness-dependent angle-resolved photoemission spectroscopy. Both ΔEEX and TC decreased monotonically with decreasing film thickness. The band shift showed an opposite thickness dependence at the Γ and X points, reflecting the balance of the hybridization between the Eu 4f and O 2p states (super-exchange interaction) and between the Eu 4f, O 2p, and Eu 5d states (indirect-exchange interaction). The observed transition from an indirect energy gap in the bulk to a direct gap in the ultrathin films of the ferromagnetic semiconductor EuO could be potential in future spintronic devices.
Funder
Japan Society for the Promotion of Science
Subject
Electrical and Electronic Engineering,Computer Science Applications,Biomedical Engineering,Atomic and Molecular Physics, and Optics,Electronic, Optical and Magnetic Materials