Effect of disorder on the magnetic and electronic structure of a prospective spin-gapless semiconductor MnCrVAl

Authors

P. Kharel, South Dakota State University
J. Herran, University of Northern Iowa
P. Lukashev, University of Northern Iowa
Y. Jin, University of Nebraska - Lincoln
J. Waybright, University of Nebraska - Lincoln
S. Gilbert, South Dakota State University
B. Staten, University of Northern Iowa
P. Gray, University of Northern Iowa
S. Valloppilly, University of Nebraska - LincolnFollow
Y. Huh, South Dakota State University
D. J. Sellmyer, University of Nebraska - LincolnFollow

ORCID IDs

J. Waybright

Date of this Version

2017

Citation

AIP Advances 7, 056402 (2017)

Comments

© 2016 Author(s).

Open access

https://doi.org/10.1063/1.4972797

Abstract

Recent discovery of a new class of materials, spin-gapless semiconductors (SGS), has attracted considerable attention in the last few years, primarily due to potential applications in the emerging field of spin-based electronics (spintronics). Here, we investigate structural, electronic, and magnetic properties of one potential SGS compound, MnCr-VAl, using various experimental and theoretical techniques. Our calculations show that this material exhibits ≈ 0.5 eV band gap for the majority-spin states, while for the minority-spin it is nearly gapless. The calculated magnetic moment for the com- pletely ordered structure is 2.9 μ_B/f.u., which is different from our experimentally measured value of almost zero. This discrepancy is explained by the structural disorder. In particular, A2 type disorder, where Mn or Cr atoms exchange their positions with Al atoms, results in induced antiferromagnetic exchange coupling, which, at a certain level of disorder, effectively reduces the total magnetic moment to zero. This is consistent with our x-ray diffraction measurements which indicate the presence of A2 disorder in all of our samples. In addition, we also show that B2 disorder does not result in antiferromagnetic exchange coupling and therefore does not significantly reduce the total magnetic moment.