Half-metallicity and magnetism of GeTe doped with transition metals V, Cr, and Mn: A theoretical study from the viewpoint of application in spintronics

Abstract

This work presents results for the magnetic properties of the compound GeTe doped with 3d transition metals V, Cr and Mn from the viewpoint of potential application in spintronics. We report a systematic density-functional study of the electronic structure, magnetic and cohesive properties of these ternary compounds in both rock salt and zinc blende structures. In both cases, it is the Ge sublattice that is doped with the three transition metals. Some of these compounds are found to be half-metallic at their optimized cell volumes. For these particular cases, we calculate both exchange interactions and the Curie temperatures in order to provide some theoretical guidance to experimentalists trying to fabricate materials suitable for spintronic devices. Discussions relating our results to the existing experimental studies are provided whenever applicable and appropriate. Apparent discrepancy between experimental observations and our theoretical result for the case of Mn-doping is discussed in detail, pointing out various physical reasons and possible resolutions of the apparent discrepancy.

Electronic Structure and Spin Configuration Trends of Single Transition Metal Impurity in Phase Change Material

“…From the above calculated LDOSs and the orbital interaction description of each TM doped rGeSb2Te4/r-GeTe, we see that from early transition metal Cr to heavier Ni, the majority 3d states are gradually populated until fully occupied and then the minority 3d states begin to be filled. This trend generally agrees with that predicted by the LDA [14][15][16][17][18][19]. Note that in ref.…”

“…The majority d states are significantly lower than the p states of the neighboring Te and the minority d states are high in energy. This is in contrast to previous LDA results [14][15][16][17][18][19] where the 3d states are described as too shallow, resulting in a large hybridization with the host p states. The integral DOS shows that the majority Fe d states are fully occupied by five electrons and the minority Fe d states are empty.…”

“…The above discussion is based on the hybrid functional calculated electronic structures. Using LDA/GGA calculated electronic structures, however, could give totally different magnetic properties and orbital interaction description, as have been done previously [14][15][16][17][18][19]. We briefly summarize the LDA results and the interpretation therein.…”

“…The upper part of the valence band comprises of p states, roughly 2/3 from Te and 1/3 from Ge for GeTe, 2/9 from Ge, 1/3 from Sb and 4/9 from Te for GeSb1Te4 from the integral DOS (not shown), in line with the stoichiometry. It has been found that TM substitution at the Ge or Sb site is energetically favorable [14][15][16][17][18][19]. It can be viewed as the interplay between elemental TM atom and Ge or Sb vacancy.…”

“…Therefore, the local and total magnetic moments are both 5μB. This orbital interaction description based on the LDA electronic structures is further simplified to an ionic model [14][15][16][17][18][19] that the Fe donates two and three electrons upon substitution of Ge and Sb, respectively, in order to form bonds with Te. The resulting electronic configurations of Fe 2+ and Fe 3+ ion are 3d 6 and 3d 5 , respectively.…”