Aurelija Mockuté

A Nanolaminated Magnetic Phase: Mn2GaC

We report on first principles prediction and subsequent synthesis of Mn2GaC, a new member of the inherently nanolaminated Mn+1AXn (MAX) phase family. This phase, the first to include Mn as the sole M element, was synthesized as a heteroepitaxial thin film. The material was theoretically predicted to display magnetic ordering with ferromagnetic (FM) and antiferromagnetic configurations degenerate in energy within the computational accuracy. Vibrating sample magnetometer measurements show FM ordering with a saturation moment of ms=0.29 μB per Mn atom and remanent moment of mr=0.15 μB per Mn atom for temperatures≤230 K.

Solid Solubility and Magnetism upon Mn Incorporation in the Bulk Ternary Carbides Cr2AlC and Cr2GaC

Herein, we report on the bulk synthesis of (Cr 1−xMn x)2AlC and (Cr1−yMny)2GaC MAX phases. Scanning electron and transmission electron microscopy, in combination with energy-dispersive X-ray spectroscopy performed locally on MAX phase grains, revealed x and y to be 0.06 (3 at%) and 0.3 (15 at%), respectively. The introduction of Mn into the structure did not result in appreciable changes in the c-lattice constants. Vibrating sample magnetometry measurements suggest that bulk (Cr0.7Mn0.3)2GaC may be magnetic.

Thin film synthesis and characterization of a chemically ordered magnetic nanolaminate (V,Mn)3GaC2

We report on synthesis and characterization of a new magnetic nanolaminate (V,Mn)3GaC2, which is the first magnetic MAX phase of a 312 stoichiometry. Atomically resolved energy dispersive X-ray mapping of epitaxial thin films reveals a tendency of alternate chemical ordering between V and Mn, with atomic layers composed of primarily one element only. Magnetometry measurements reveal a ferromagnetic response between 50 K and 300 K, with indication of a magnetic ordering temperature well above room temperature.

Structural and magnetic properties of (Cr1−xMnx)5Al8 solid solution and structural relation to hexagonal nanolaminates

Electron microscopy is used to reveal the competitive epitaxial growth of bcc structure (Cr1−xMnx)5Al8 and (Cr1−yMny)2AlC [Mn+1AXn (MAX)] phase during both magnetron sputtering and arc deposition. X-ray diffraction θ–2θ measurements display identical peak positions of (000n)-oriented MAX phase and (Cr1−xMnx)5Al8, due to the interplanar spacing of (Cr1−xMnx)5Al8 that matches exactly half a unit cell of (Cr1−yMny)2AlC. Vibrating sample magnetometry shows that a thin film exclusively consisting of (Cr1−xMnx)5Al8 exhibits a magnetic response, implying that the potential presence of this phase needs to be taken into consideration when evaluating the magnetic properties of (Cr, Mn)2AlC.