Thermodynamics, electronic, and magnetic properties of Cr-doped Cr2CoAl: Biaxial ([110]) strain impact

Highly spin-polarized materials are extremely desired for the designing of magnetic tunnel junctions, which have potential utilization in data storage devices. Herein, ab-initio calculations were performed to investigate the thermodynamics, electronic, and magnetic properties of inverse full-Heusler Cr2Co1-xCrxAl (x = 0%, 12.5%, 25%, 37.5%, and 50%) compound under the influence of biaxial strain along the [110]-direction. Formation energies confirm the experimental realization of the structures by assuming the chemical potentials of ions in their respective stable phases and utilizing the Convex Hull analysis. The calculated elastic properties affirm that all the motifs are mechanically stable, ductile, and anisotropic. Moreover, positive frequencies of phonon band structures established the dynamical stability of the systems. The ground state of the unstrained pristine Cr2CoAl system is a ferrimagnetic (FiM) metallic due to strong antiferromagnetic coupling between the Cr1/Co and Cr2 ions. Furthermore, our results revealed that the total magnetic moment and spin-polarization get reduced as the Cr-concentration increases, which endorses the recent experimental observations Srivastava et al., 2020. Strikingly, the undoped structure displayed a transition from FiM to non-magnetic state for biaxial compressive strains along the ab-plane due to strong hybridization between ions, while retaining its FiM nature for tensile strains. On the other hand, all the Cr-doped systems flow towards degeneracy by maintaining their magnetic metallic states as the compressive strain strength increases. However, all the tensile strained structures sustained their magnetic metallic nature. Hence, the present work suggested that the combined effect of doping and strain substantially modulated the physical properties of the Heusler structures.

Automated summary

This study investigates the thermodynamics, electronic, and magnetic properties of Cr2Co1-xCrxAl compound under biaxial strain using ab-initio calculations. The results show that the combined effect of doping and strain significantly modifies the physical properties of the Heusler structures.