Characterization of quaternary Heusler alloys CoFeYGe (Y = Ti, Cr) with respect to structural, electronic, magnetic, mechanical, and thermoelectric features


Charifi Z., Ghellab T., Baaziz H., Soyalp F.

INTERNATIONAL JOURNAL OF ENERGY RESEARCH, 2022 (Journal Indexed in SCI) identifier identifier

  • Publication Type: Article / Article
  • Publication Date: 2022
  • Doi Number: 10.1002/er.8104
  • Title of Journal : INTERNATIONAL JOURNAL OF ENERGY RESEARCH
  • Keywords: figure of merit, half-metals, improving ZT, quaternary Heusler alloys, HALF-HEUSLER, TRANSPORT-PROPERTIES, SPIN-POLARIZATION, 1ST PRINCIPLES, SI, 1ST-PRINCIPLES, GE, GA, AL, FE

Abstract

The electronic, magnetic, elastic, and thermoelectric properties of CoFeYGe (Y = Ti, Cr) quaternary Heusler compounds are studied using DFT simulations. Our calculations show that both CoFeYGe (Y = Ti, Cr) alloys have a Type-I atomic configuration. CoFeCrGe and CoFeTiGe compounds with band gaps of 0.640 eV and 0.489 eV, respectively, were found to display half-metallic behavior in the minority spin channels. The total magnetic moment of CoFeCrGe was 3.00 mu(B), while CoFeTiGe's was 1.00 mu(B). CoFeTiGe and CoFeCrGe are both mechanically stable in the Y-Type-I structure. The surface of E is entirely distorted, demonstrating substantial anisotropy for two compounds. They have a higher anisotropic Young's modulus in the (XY), (XZ), and (YZ) planes. At 900 K, ZT is 0.31706 (0.45308) for CoFeTiGe (CoFeCrGe), corresponding to a carrier concentration of n(0) = 20.4581 x 10(21) cm(-3) (64.5856 x 10(21)) cm(-3). Two ways exist to enhance ZT values of CoFeTiGe and CoFeCrGe to 0.4032 and 0.64149, respectively: A charge carrier concentration of 17.392 x 10(21) cm(-3) for CoFeTiGe and 59.503 x 10(21) cm(-3) for CoFeCrGe is obtained. The second similar result is obtained by raising the chemical potential of CoFeTiGe and CoFeCrGe by 0.068 and 0.980 Ryd, respectively. To our knowledge, CoFeCrGe and CoFeTiGe exhibit exceptional spintronic and thermoelectric properties.