First-principles investigation of magneto-electronic properties and band Jahn-Teller effects in NiCoMnSi1-xAlx quaternary Heusler

Abstract

Using ab initio calculations, density functional theory (DFT) calculations have been performed to investigate the electronic
and magnetic properties of NiCoMnSi1-xAlx (x=0, 0.25, 0.50, 0.75 and 1) quaternary Heusler compounds. To check the
evolution of band Jahn teller effect in quaternary Heusler alloy and known the main raison to get the ground state energy by
deforming the martensitic phase, we focused our work on the structural stability related to the formation of a Heusler alloy
from two different crystallographic structures (cubic and tetragonal), for different concentrations. The structural, electronic
and magnetic properties are calculated for all concentrations in both cubic and tetragonally distorted structure. Variation of
total energy versus volume indicates that the crystallographic structures shift the cubic shape from a concentration of 0.50,
which can be essential due to the Jahn-Teller effect. Magnetic properties of all studied alloys give the total magnetic moment
of 4.086 μB, 4.561 μB, 5.024 μB, 5.092 μB and 5.000 μB respectively. With an integer value of total magnetic moment,
NiCoMnAl alloy has a 100% spin polarisation at Fermi level with a half-metallic behaviour.