Structural insight using anomalous XRD into Mn2CoAl Heusler alloy films grown by magnetron sputtering, IBAS, and MBE techniques

Inverse Heusler alloy Mn 2 CoAl thin films, known as a spin-gapless semiconductor (SGS), grown by three different methods-ultra-high vacuum magnetron sputtering, Ar-ion beam assisted sputtering, and molecular beam epitaxy-are investigated by comparing their electric transport properties, microstructures and atomic-level structures. Of the samples, the Mn 2 CoAl thin film grown by molecular beam epitaxy consists of Mn- and Co-rich phases, the structures of which are determined to be the L 2 1 B -type and disordered L 2 1 -type, respectively, according to anomalous X-ray diffraction analysis. None of them forms the X A type structure expected for SGS Heusler alloy, although they all exhibit SGS characteristics. To validate the SGS characteristics, it is necessary to extract not only the magnetic and electric transport properties but also information about microstructures and atomic-scale structures of the films including defects such as atomic swap.

Automated summary

Inverse Heusler alloy Mn2CoAl thin films, known as spin-gapless semiconductors (SGS), were grown by three different methods and their properties were investigated. Although all the samples exhibited SGS characteristics, none of them formed the expected structure.