Investigation of Magnetic Anisotropy and Heat Dissipation in Thin Films of Compensated Antiferromagnet CuMnAs by Pump-probe Experiment.

Recently, the possibility to determine the easy axis position in 10 nm thick film of compensated antiferromagnet CuMnAs with in-plane uniaxial magnetic anisotropy by magneto-optical pump and probe experiment was reported [Nature Photonics 11, 91 (2017)]. In this contribution we discuss the applicability of this method for the investigation of a broader set of epitaxial CuMnAs films having different thicknesses. It was revealed that the in-plane magnetic anisotropy can be studied only in samples where this anisotropy is rather strong. On the other hand, in samples with a weak magnetic anisotropy the impact of a strong pump pulse itself induces considerable anisotropy changes and, therefore, the magnetic anisotropy measured by the pump-probe technique differs substantially from that in the equilibrium conditions. However, the major achievement reported in this paper is that optical pump-probe experiment can be used very efficiently to study the local heating and heat dissipation in CuMnAs epitaxial layers. In particular, it was revealed that for a local film heating by a focused laser the thinner films are heated more but the heat is dissipated considerably faster than in the case of thicker films. This illustrates that optical pump-probe experiment is a valuable characterization tool for the heat management optimization in the CuMnAs memory devices and can be applied in a similar way as was used previously during the heat-assisted magnetic recording (HAMR) technology development for a latest generation of hard drive discs.