Coupling of Magnetic Layers in (CrMn)2GaC MAX Phases investigated by the combination of XLD and XMCD

The aim of the study is the understanding of magnetic coupling and resulting electronic changes in the atomically-layered magnetic (Mn1-xCrx)2GaC MAX phase system. Due to complex non-collinear antiferromagnetic coupling driven by competing antiferromagnetic (AFM) and ferromagnetic (FM) interlayer exchange over the Ga layer, a rich phase diagram has been obtained. For Mn2GaC, this is accompanied by huge magnetostriction (450 ppm in 3 T) with sign inversion at the 1st order phase transition around 220 K. Substituting Cr for Mn weakens the interlayer coupling resulting in reduced ordering temperatures from ~500 K for Mn2GaC to ~200 K for (Mn0.5Cr0.5)2GaC and already moderate external fields (~0.3 T) can break the AFM coupling between FM ordered (Mn,Cr)-C-(Mn,Cr) sheets. Laboratory-based structural and magnetic studies have risen the hypothesis that the coupling depends on the local Mn environment which should be addressed by hard X-ray Linear Dichroism (XLD) and XMCD.