Regensburg 2013 – scientific programme
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MA: Fachverband Magnetismus
MA 27: Magnetic Thin Films II of 2
MA 27.7: Talk
Wednesday, March 13, 2013, 16:45–17:00, H3
Straining epitaxial Fe-Co thin films to increase magnetocrystalline anisotropy — •Ludwig Reichel1,2, Sandra Kauffmann-Weiss1,2, Ludwig Schultz1,2, and Sebastian Fähler1 — 1IFW Dresden, PF 270116, 01171 Dresden — 2TU Dresden, 01062 Dresden
The demand on permanent magnets is strongly increasing and alternatives to the common rare-earth based alloys lack. Fe-Co alloy is a promising candidate as it provides already a very high magnetic moment. High magnetocrystalline anisotropy is expected when its equilibrium cubic unit cell is strained tetragonally with (c/a)bct around 1.2 [1,2].
In the present investigation, epitaxial Fe-Co films between 1 and 10 nm thickness were deposited at room temperature using pulsed laser or magnetron sputtering deposition. Different buffer layers were used to provide the required in-plane lattice parameter a. As the unit cell volume should remain constant, the out-of-plane lattice parameter c is expected to adapt accordingly. In situ diffraction of high energetic electrons (RHEED) during film growth allows us to monitor the epitaxial growth and the relaxation of strain which begins at a critical film thickness dC. Out-of-plane magnetic hysteresis measurements exploiting the anomalous Hall effect are compared with the in situ results. Both methods show that the critical thickness does not exceed few nanometers for the described approach.
[1] Burkert et al. Phys. Rev. Let. 93 (2004) 027203
[2] Neise et al. Phys. Status Solidi B 248 (2011) 2398
This work is funded by the European Union through REFREEPERMAG-FP7.