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All sourcesNASA NTRSDOE OSTI
DOE OSTI2020

Materials Data on CrGa(BiO3)2 by Materials Project

CrGa(BiO3)2 is Ilmenite-derived structured and crystallizes in the trigonal R3 space group. The structure is three-dimensional. Cr3+ is bonded to six O2- atoms to form CrO6 octahedra that share corners with six equivalent GaO6 octahedra. The corner-sharing octahedral tilt angles are 25°. There are three shorter (2.01 Å) and three longer (2.06 Å) Cr–O bond lengths. Ga3+ is bonded to six O2- atoms to form GaO6 octahedra that share corners with six equivalent CrO6 octahedra. The corner-sharing octahedral tilt angles are 25°. There are three shorter (1.97 Å) and three longer (2.08 Å) Ga–O bond lengths. There are two inequivalent Bi3+ sites. In the first Bi3+ site, Bi3+ is bonded in a 6-coordinate geometry to six O2- atoms. There are three shorter (2.35 Å) and three longer (2.47 Å) Bi–O bond lengths. In the second Bi3+ site, Bi3+ is bonded in a 6-coordinate geometry to six O2- atoms. There are three shorter (2.37 Å) and three longer (2.46 Å) Bi–O bond lengths. There are two inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted see-saw-like geometry to one Cr3+, one Ga3+, and two Bi3+ atoms. In the second O2- site, O2- is bonded in a distorted see-saw-like geometry to one Cr3+, one Ga3+, and two Bi3+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on CrGa by Materials Project

CrGa crystallizes in the trigonal R-3m space group. The structure is three-dimensional. there are three inequivalent Cr sites. In the first Cr site, Cr is bonded to six equivalent Cr and six equivalent Ga atoms to form CrCr6Ga6 cuboctahedra that share faces with two equivalent GaCr12 cuboctahedra. All Cr–Cr bond lengths are 2.47 Å. All Cr–Ga bond lengths are 2.62 Å. In the second Cr site, Cr is bonded in a 12-coordinate geometry to five Cr and seven Ga atoms. There are a spread of Cr–Cr bond distances ranging from 2.50–2.79 Å. There are a spread of Cr–Ga bond distances ranging from 2.54–2.69 Å. In the third Cr site, Cr is bonded in a 12-coordinate geometry to six Cr and six Ga atoms. Both Cr–Cr bond lengths are 2.65 Å. There are a spread of Cr–Ga bond distances ranging from 2.48–2.70 Å. There are three inequivalent Ga sites. In the first Ga site, Ga is bonded to twelve Cr atoms to form GaCr12 cuboctahedra that share faces with two equivalent CrCr6Ga6 cuboctahedra. In the second Ga site, Ga is bonded in a 1-coordinate geometry to six Cr and five Ga atoms. There are a spread of Ga–Ga bond distances ranging from 2.60–3.00 Å. In the third Ga site, Ga is bonded in a 6-coordinate geometry to six Cr and two equivalent Ga atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2022

Emergence of asymmetric skew-scattering dominated anomalous Nernst effect in the spin gapless semiconductors Co 1+x Fe 1-x CrGa

Heusler alloy-based spin gapless semiconductors (SGSs) with very high Curie temperatures ( T C ) have recently gained enormous attention because of their unconventional electronic structures. They exhibit a nonzero band gap in one of the spin channels and a zero band gap in the other spin channel, making them an important class of materials for tunable spin transport. Here, we report the experimental observation of anomalous Nernst effect (ANE) in Co 1 + x Fe 1 - x CrGa ( x = 0 , 0.2, 0.4, and 0.5), which are the emerging quaternary Heusler alloy-based SGSs. While the electron-electron elastic scattering and the disorder-mediated weak localization effect play the major roles in electrical transport for all the samples at low temperatures, the magnon-drag effect was found to dominate the longitudinal thermoelectric transport. The ANE coefficient at room temperature increases from ≈ 0.018 μ V K - 1 for x = 0 to ≈ 0.063 μ V K - 1 for x = 0.5 , which is higher than that for Ni 81 Fe 19 and compressively strained SrRu O 3 films. Our analysis indicates that the observed ANE in these samples originates from asymmetric skew scattering of charge carriers.

36 MATERIALS SCIENCE↗