Magnetic ordering and magnetocrystalline anisotropy in epitaxial Mn2GaC MAX phase thin films

Abstract

${\mathrm{Mn}}_{2}\mathrm{GaC}$ is a MAX phase belonging to a family of naturally nanolaminated materials with formula ${M}_{n+1}A{X}_{n}$ ($n=1,2,3$), where $M$ is a transition metal, $A$ is an A-group element, and $X$ is carbon or nitrogen. It has a complex magnetic phase diagram, and there are many open questions regarding its magnetic properties. Here we study epitaxial films of ${\mathrm{Mn}}_{2}\mathrm{GaC}$ with two different crystal orientations on MgO(1 1 1) substrates: a (0 0 0 l) dominated orientation and a mixed (0 0 0 l) and (1 0 $\overline{1}$ 3) orientation. Magnetic measurements between 3 and 320 K are presented for in-plane and out-of-plane magnetic fields on both types of film, which show that ${\mathrm{Mn}}_{2}\mathrm{GaC}$ has a magnetocrystalline anisotropy with (0 0 0 l) as easy planes. This provides clear experimental evidence of the anisotropic properties associated with the nanolaminated structure of a MAX phase. In addition, a close look at the magnetic response at low temperature shows that the noncollinear magnetic state is unchanged below 50 K, contrary to previous results, with a magnetic moment of 0.38 ${\ensuremath{\mu}}_{B}$ per Mn atom at a temperature of 3 K and applied field of 5 T.