  We recently reported on a method to determine the easy axis position in a 10
nm thick film of the fully compensated antiferromagnet CuMnAs. The film had a
uniaxial magnetic anisotropy and the technique utilized a magneto-optical pump
and probe experiment [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. This work reveals that
the equilibrium magnetic anisotropy can be studied only in samples where this
anisotropy is rather strong. However, in the majority of CuMnAs films, the
impact of a strong pump pulse induces nano-fragmentation of the magnetic
domains and, therefore, the magnetic anisotropy measured by the pump-probe
technique differs substantially from that in the equilibrium conditions. We
also demonstrate that optical pump-probe experiment can be used very
efficiently to study the local heating and heat dissipation in CuMnAs epitaxial
layers. In particular, we determined the electron-phonon relaxation time in
CuMnAs. We also observed 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 the 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
to those used during heat-assisted magnetic recording (HAMR) technology
development for the latest generation of hard drive disks.
