Effect of carbon co-doping on magnetic properties of transition and rare-earth metal-doped bismuth telluride

We investigated the magnetic interaction of carbon (C)-transition (Cr/Fe) and rare-earth Gadolinium (Gd) metal co-doped bismuth telluride (BT) systems (Cr x C y Bi 12− x Te 18− y , Fe x C y Bi 12− x Te 18− y and Gd x C y Bi 12− x Te 18− y ( x = 1, y = 1) supercell structures) by using the density functional theory based on the full-potential linear augmented plane wave method via inclusion of spin polarized calculation. Addition of metal dopant ions in bismuth telluride enhanced the total spin magnetic moment of the entire system ( M tot ), which was further increased by the presence of the carbon ion. However, spin magnetic moment of individual dopant ions ( M S ) was found to be increased or decreased depending upon the position of the metal-carbon dopants relative to each other. This increase in M S is explained by Zener exchange mechanism. C showed a weak M S , in its addition in the BT system. Gd-C co-doping showed highest M tot and M S compared to Fe-C doped (BT) system. The spin magnetic moment of the system and that of individual dopant ions is influenced by varying the position of C relative to metal dopant ions in BT system. This understanding over the changes in the value of magnetic moment with respect to the position of C ion compared to other dopant ions in the material will lead to the future improvement of magnetic data storage devices. Graphical abstract