J Phys Condens Matter. 2013 Jun 26;25(25):256007. doi: 10.1088/0953-8984/25/25/256007. Epub 2013 Jun 06.

Room-temperature ferromagnetism of all-epitaxial β-Fe-Ge/diamond-Ge/β-Fe-Ge trilayers.

Journal of physics. Condensed matter : an Institute of Physics journal

I Maafa, S Hajjar-Garreau, R Jaafar, D Berling, C Pirri, A Mehdaoui, E Denys, A Florentin, G Garreau

PMID: 23740804 DOI: 10.1088/0953-8984/25/25/256007

Abstract

We report on the first all-epitaxial ferromagnet/inorganic semiconductor/ferromagnet hybrid heterostructure that exhibits (i) a Ge barrier of diamond crystal structure, (ii) room-temperature ferromagnetic electrodes and (iii) very smooth interfaces. Both bottom- and top-Fe-Ge electrodes exhibit tiny in-plane magnetic anisotropies dominated by a magnetocrystalline contribution of six-fold symmetry originating from the hexagonal symmetry of the B82 (Ni2In) β-Fe-Ge phase. A key result is the absence of any magnetic coupling between these soft-magnetic electrodes for Ge barrier thickness as low as ~2.5 nm, which allows us to easily tune the parallel and antiparallel magnetic alignments by applying suitably small magnetic fields. This confirms the beneficial use of H-surfactant in order to drastically reduce the roughness of the Ge barrier, as revealed by our scanning tunneling microscopy and transmission electron microscopy measurements. This new all-epitaxial ferromagnet/semiconductor hybrid system appears, therefore, to be a promising candidate for the realization of magnetic tunnel junctions with a single crystal semiconductor barrier that are fully compatible with Si-based technology.

Publication Types

• Journal Article
• Research Support, Non-U.S. Gov't