Dresden 2014 – wissenschaftliches Programm
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MA: Fachverband Magnetismus
MA 28: Magnetic Materials I
MA 28.3: Vortrag
Mittwoch, 2. April 2014, 15:30–15:45, HSZ 04
Fe-Co-X films with spontaneous strain and increased magnetocrystalline anisotropy — •Ludwig Reichel1,2, George Giannopoulos3, Martin Hoffmann1,2, Steffen Oswald1, Dimitris Niarchos3, Ludwig Schultz1,2, and Sebastian Fähler1,4 — 1IFW Dresden, PF 270116, 01171 Dresden — 2TU Dresden, 01069 Dresden — 3Demokritos NCSR, 15310 Athens, Greece — 4TU Chemnitz, 09107 Chemnitz
Permanent magnets are ubiquitous. Within the last years, abundance of the rare-earth based alloys has been questioned, but alternatives are still missing. Fe-Co alloy was considered a promising candidate as it provides a very high magnetic moment. A remarkable magnetocrystalline anisotropy (MCA), which is a condition for permanent magnets, is proposed when its cubic unit cell is strained tetragonally [1]. However, in thin films, the strain relaxes within few monolayers. Recently, it was proposed that a low fraction of carbon atoms stabilises the strain and leads to a high MCA [2].
In this study, interstitials as C and B were alloyed to Fe-Co. The films were prepared using PLD. In situ RHEED allowed for an investigation of film relaxation. It was observed, that the relaxation stopped at a c/a ratio of approx. 1.03 i.e. tetragonally distorted. This residual strain is also present in films of thicknesses up to 100 nm and indicates the formation of spontaneously strained Fe-Co-X films. Magnetic measurements demonstrate the influence of strain on magnetic anisotropy.
[1] Burkert et al. Phys. Rev. Let. 93 (2004) 027203
[2] Delczeg-Czirjak et al. submitted (2013)