November 07, 2022
Minneapolis, United States
Effect of substitution of 3d, 4d and 5d elements on structural, electronic, magnetic properties and XMCD spectra of Co based Full Heusler alloys: A DFT Study
The promising properties of Co-based (i.e. Co2BC) Heusler alloys (HA) such as half-metallicity, magneto-caloric effect, shape-memory effect, spin-valve like behavior, etc. make them important from technological as well as fundamental point of view.1-5 In the present work, we have probed the role of substitution of 3d, 4d and 5d elements (i.e, with electronic configuration (EC): ndx where n = 3-5 ; x = number of electrons in d level) at the B site on structural, magnetic and electronic properties of a set of Co-based full HAs using DFT based first principle calculations.
We have optimized all the 30 combinations studied here in Fm-3m (A2BC conventional HA structure) and F-43m (AABC inverse HA structure) space groups using VASP.6 Thereafter, electronic structure (ES) calculations have been carried out using FPLAPW method as implemented in WIEN2k7 and results obtained using PBE and mBJ exchange-correlation terms have been compared. Further, XMCD calculations have been performed using single particle approximation and Fermi-golden rule as implemented in WIEN2k7.
It is observed that the HAs with EC: nd1-6,10 (n = 3, 4, 5) at B site have Fm-3m as the lowest energy structure. Calculated magnetic moment of these alloys with EC: nd1-6 are found to be in agreement with the Slater-Pauling (SP) rule with an integer or close to integer value, except 4d1, 4d6 and 5d6 as shown in Figure 1. Furthermore, alloys with EC: nd2-6 show half-metallic or half-metallic nature. However, alloys having EC: nd7-9 (along with 4d1 and 4d6) at B site are found to be in F-43m space group. Further, magnetic moment of EC: nd7-10 show deviation from the SP rule. In order to understand the impact of nd1-10 electrons on the local environment of various atomic sites, detailed analyses of the XMCD spectra have been carried out on the basis of changes in the orbital projected unoccupied density of states.
1. T. Roy, et al., Phys. Rev. B., 93, 184102 (2016) and references therein
2. M. Baral, et al., Phys. Rev. B., 99, 205136 (2019) and references therein
3. K. Inomata, et al., J. Appl. Phys., 95, 7234 (2004) and references therein
4. R. Dutt et al., J. Phys. Condens. Matter , 33, 045402 (2020) and references therein
5. I. Galankis, et al., Phys. Rev. B., 66, 134428 (2002) and references therein
6. G. Kresse et al., Phys. Rev. B., 54, 11169 (1996) and references therein
7. P. Blaha, et al., J. Chem. Phys. 152, 074101 (2020) and references therein