FeCrYZ (Y = Ti, Zr, & Hf and Z = Sn, and Sb) quaternary Heusler alloys for data storage, energy conversion and optoelectronics applications.

First principles electronic structural calculation of full Heusler alloys Ir2YSi (Y= Sc to Ni) in the L21 (Cu2MnAl) and Xa (Hg2CuTi) structures have been studied using full-potential linearized augmented plane wave method (FP-LAPW) based on density functional theory (DFT). From the total energy calculations, it has been observed that all these alloys are stable in L21 structure than Xa structure and also it is found that the alloys Ir2YSi (Y =V to Co) are ferromagnetically stable whereas the Ir2YSi (Y = Sc, Ti, and Ni) alloys are non-magnetic in their stable L21 structure. Spin polarized band structure calculations reveal that in Ir2YSi (Y= V to Co) alloys there is spin splitting of energy states around the Fermi level (EF) indicating ferromagnetism and moreover in Ir2YSi (Y = V, Cr, and Mn) alloys majority electrons have metallic behavior while minority electrons have semiconducting nature exhibiting half metallic ferromagnetic (HMF) nature. HMF property in Ir2YSi (Y = V, Cr, and Mn) alloys have been further confirmed from the integer total magnetic moment value of 3.0 µB, 4.0 µB and 5.0 µB per formula unit respectively. Spin polarization mainly arises from the interaction between 3d electrons of V/Cr/Mn atom and 5d electrons of Ir atom. This strong d-d hybridization between the transition atoms like Ir and V/Cr/Mn composing Heusler alloys is essential for the formation of gap at the EF between the valence and conduction bands. Our results show that Ir2YSi (Y= V, Cr, and Mn) will be suitable for ferromagnetic and spintronics applications.

The structural, electronic, magnetic, and transport properties of LiMgPdSb-type novel quaternary Heusler alloys XRuCrZ (X = Co, Ni, Rh, and Pd; Z = Si and Ge) have been studied employing the first-principles calculation derived from density functional theory. From the total energy calculations, it is found that all these alloys are stable in the cubic α phase, and spin-polarized calculations show that all the alloys favor a ferromagnetic state. In addition, it is ascertained that XRuCrZ (X = Co and Rh; Z = Si and Ge) exhibits half-metallic ferromagnetic property. In addition, the temperature-dependent transport properties have been studied. The calculated dimensionless figure of merit for CoRuCrSi is 0.43. Our results show that these alloys will be suitable for data storage and energy conversion applications.