New quaternary Heusler materials, CoMnTiAl and FeMnTiAl, have been investigated.

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Summary The tantalum‐based double perovskites Ba2MTaO6 (M = Mn, Cr) are studied to understand the effect of pressure on structural, electronic, magnetic, thermodynamic, and thermoelectric properties by means of density functional theory. Ba2MTaO6(M = Mn, Cr) perovskites' own maximum stability in ferromagnetic phase with calculated high magnetic moments of 4.02 and 3.0 μB at zero pressure. Ba2MTaO6 (M = Mn, Cr) perovskites display complete spin polarization, ensuing the half metallic behavior. Effect of high pressure on the electronic structure and magnetism was also studied. The compounds have wide band gap that varies from 2.63 to 2.56 eV as the pressure increases from 0 to 25 GPa in Ba2CrTaO6, while as in Ba2MnTaO6 band gap varies from 2.24 to 1.95 eV as the pressure increase from 0 to 25 GPa. The magnetic moment also shows a decreasing inclination with increase in pressure in both compounds. Also, we calculated the heat capacities, thermal expansion coefficients, Debye temperature and Grüneisen parameter by using the Debye model. Boltzmann's theory was employed to perform post DFT treatment to investigate the thermoelectric properties of the compounds.