Berlin 2015 – scientific programme

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MA: Fachverband Magnetismus

MA 52: Magnetic Thin Films II

MA 52.1: Talk

Friday, March 20, 2015, 09:30–09:45, H 1012

Magnetic anistropy energy of thin Fe layers on GaAs surface - the influence of defects — •Karel Carva and Ilja Turek — Charles University in Prague, Ke Karlovu 5, Prague 12116, Czech Republic

For thin Fe layers on top of GaAs surface an in-plane magnetic anisotropy energy (MAE) has been predicted, with an unusually high value. The experimental values vary by more than an order of magnitude here, which may be linked to the presence of defects, since the interface structure is not characterized sufficiently. We examine primarily the influence of intermixing between Fe and GaAs at the interface on the MAE. Interestingly, the calculated MAE does not only reduce its value with disorder, but may also change the sign. We examine more deeply the origin of this in-plane anisotropy. Layer-resolved calculations show that for this interface the contribution from the layer at the interface can be exceeded by that from more distant layers, which puts emphasis on the calculation precision.

We employ fully relativistic first-principles theory of metallic ferromagnetic systems. The theory is based on the all- electron tight-binding linear muffin-tin orbital (LMTO) method and the coherent potential approximation (CPA) is used to treat chemically disordered systems. Particular attention is devoted here to the spin and orbital magnetic moments, total energies, and transport properties. Data storage technology may significantly benefit from an increase of MAE allowing a higher data density. Understanding the dependence of MAE on various parameters allows to control it with a high precision.