Uncovering magnetic structure in the nanolaminated MAX phase (Mn,Cr)2GaC

MAX phases are a class of intrinsically nanolaminated materials which combine features of metals and ceramics, owing to the alternating metallic and covalent bonding between layers. Magnetic MAX phases have been known for a decade but ferromagnetism at room temperature has been elusive, limiting their value as magnets in practice. We have shown for the first time that a MAX phase with a strong ferromagnetic-like response is obtained by alloying with Cr on the M-site in (Mn,Cr)2GaC up to temperatures well exceeding room temperature (489 K). The exact nature of the magnetic ordering is as yet unknown but neutron diffraction measurements have shown signs of non-collinear order in films with 6 at% Cr on the M-site. However, more data is needed to complete this picture and explain the origin of the high remanent moment. We propose performing single-crystal neutron diffraction measurements at the WISH beamline to determine the magnetic ordering in two films of (Mn,Cr)2GaC which exhibit widely different magnetic properties. This will allow the continued optimization of this complex alloy, with potential applications ranging from bulk magnets in power electronics to spintronic devices.