First principle studies on novel cucrmnal quaternary heusler alloy for thermoelectric and spintronic applications

We report the structural stability, dynamical stability, feasibility of physical synthesis, electronic, magnetic, thermodynamic and thermoelectric properties of novel CuCrMnAl quaternary Heusler alloys using first principle studies based on density functional theory (DFT). CuCrMnAl alloy is found to be stable in cubic phase with equilibrium lattice constant 5.6568Å, fitted with Birch-Murnaghan equation of state. When compared to Non- magnetic and Ferromagnetic states, Ferri-magnetic state is stable due to large negative energy. The observed negative formation energy (-3.8066 eV) makes this alloy a physically synthesizable compound. Further non-zero density of states (DOS) in spin-down channels and zero density of states in spin-up channel near to Fermi energy prove its half- metallic character. Absence of imaginary frequencies in phonon dispersion spectrum confirms the dynamical stability of the compound. Integration of DOS indicates the magnetic moment of a compound and estimated magnetic moment is 0.98µB. It is observed that major contribution for magnetic moment is coming from Mn atoms. It can be observed that strong bonding between Mn-Ni atoms are due to stronger Heisenberg’s exchange coupling strength. The calculations of different thermodynamic properties such as entropy, free energy and specific heat at constant volume (CV) of CuCrMnAl alloy are performed by varying the temperature from 0 K to 2000 K. To estimate thermoelectric properties of CuCrMnAl alloy as a function of chemical potential and temperature, we have used the BoltzTrap code based on the Boltzmann model via Boltzmann transport equation. The figure of merit (ZT) is very large of 0.5 at 400K as calculated thermal conductivity is low and Seebeck coefficient is large value and also power factor also reasonably good, shows that our CuCrMnAl alloy can be used for powerful thermoelectric devices. The figure of merit further enhanced by reducing lattice contribution to thermal conductivity, this could be possible by annealing sample under proper conditions leads to adjustment of its crystallographic order. Mn-Ni based samples usually are high entropy heusler alloys can be used as efficient magnetic refrigerant materials.