Band engineering of modified rhombohedral Cu₄Mn₂Te₄: ab initio approach

ABSTRACT

Systematic band structure calculations are reported for the first time on the ‘modified rhombo (R-3 m) structured Cu₄Mn₂Te₄’ compound by adapting the Lotgering model. Wyckoff positions of all the atoms are estimated. There is a good agreement between the present computed lattice parameter values with the already reported. Mechanism of phase transition from Fd-3m structure (3Cu added spinel CuMn₂Te₄) to R-3m structure (distorted rhombo Cu₄Mn₂Te₄) at room temperature is discussed. Spin-polarised calculations reveal Cu₄Mn₂Te₄ energetically prefers the AFM phase at ambient conditions. Band structures predict the compound to be of metallic nature at its NM and FM phases whereas a band gap opening occurs at its AFM phase. Band gap value is estimated as ∼ 0.2 eV and ∼0.7 eV using GGA and mBJ exchange–correlation schemes, respectively. Origin of band gap opening is discussed. Total spin magnetic moment (µ_B) per formula unit of Cu₄Mn₂Te₄ compound is calculated as 9.878 and −5.001, respectively, at FM and AFM phases. Electrical conductivity is enhanced by a factor of 10² from 100 K to 300 K at minority spin states. Maximum optical conductivity occurs at 6500 Ω⁻¹cm⁻¹ which lies in the visible region of the electromagnetic spectrum.

KEYWORDS:

• Phase transition
• anti-ferromagnetism
• band gap
• electronic structure
• optical properties
• Lotgering model

Acknowledgements

Authors wish to acknowledge the Department of Science and Technology (DST), Government of India via SR/FST/psi-193/2014 to carry out the present work.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Correction Statement

This article has been republished with minor changes. These changes do not impact the academic content of the article.