Epitaxial Growth of Fe Thin Films on MgO Single-Crystal Substrates

Abstract

Fe thin films were prepared on MgO(100), MgO(110), and MgO(111) substrates by UHV-MBE. The film growth structure and the magnetic properties were investigated. In-situ RHEED observation showed that epitaxial Fe thin film with the (100)_bcc, (211)_bcc, and (110)_bcc planes parallel to the substrate surface grew on respective MgO substrates at elevated temperatures. The Fe(100)_bcc film formed on MgO(100) is a single crystal, while the Fe(211)_bcc films on MgO(110) consists of two domains with a twin relationship. The Fe(110)_bcc film on MgO(111) consists of two types of sub-domains with Nishiyama-Wasserman and Kurdjumov-Sachs epitaxial orientation relationships. A 0.3%-0.5% reduction of the lattice spacing perpendicular to the substrate surface was observed by X-ray diffraction for Fe thin films prepared at a substrate temperature of 200°C. This reduction decreases with increasing the substrate temperature for the MgO(100) and (111) substrates. The in-plane magnetic anisotropy measured for three epitaxial films reflects the magneto-crystalline anisotropy of bulk Fe crystal.