Regensburg 2004 – scientific programme

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MA: Magnetismus

MA 20: Magnetische dünne Schichten II

MA 20.6: Talk

Thursday, March 11, 2004, 11:30–11:45, H10

Thin epitaxial films of the Heusler compound Co₂Cr_0.6Fe_0.4Al — •Gerhard Jakob¹, Frederick Casper^1,2, Virginie Beaumont^1,2, Stefan Falk¹, Hans-Joachim Elmers¹, and Claudia Felser² — ¹Institut für Physik, Universität Mainz, Staudinger Weg 7, 55099 Mainz — ²Institut für Anorganische und Analytische Chemie, Universität Mainz, Düsbergweg 10-14, 55099 Mainz

A tunnel magnetoresistive element has recently been reported based on thin polycrystalline films of the Heusler compound Co₂Cr_0.6Fe_0.4Al [1]. According to band structure calculations this material is half metallic, i.e. there exists only one spin direction for the charge carriers at the Fermi edge. We prepared thin epitaxial films of this compound in the B2 structure on a-plane (1120) Al₂O₃ substrates by sputtering. Films grown at high temperatures (T=600^oC) are fully epitaxial with the (110) and (110) planes of the film parallel to the (1120) and (0001) planes of the substrate, respectively. The films show nearly rectangular hysteresis loops with coercitive fields of the order of 10mT. Magnetooptical Kerr measurements show an in-plane anisotropy of the magnetization with the easy axis in {001} direction. Hall measurements show a strong anomalous Hall effect and a weak normal Hall voltage signalling the existence of a compensated Fermi surface.

[1] K. Inomata et al., Jpn. J. Appl. Phys. 42, L419 (2003)