Strain-driven electronic and thermoelectric modulation in Cs2CuMoX6 (X = Cl, Br) halide double perovskites

초록

Halide-based double perovskites under biaxial strain propose a profound insight into their electronic and magnetic characteristics and emerge as a potential aspirant for spintronic applications. In this examination, the structural, electronic, magnetic, optoelectronic, and thermoelectric characteristics of Cs2CuMo (Cl/Br)6 have been studied under biaxial strain by employing the WIEN2k software. The lattice constant value has been enhanced from 10.01 to 10.53 & Aring; by substituting Cl with Br for an optimized FCC lattice. Their thermodynamic stability is affirmed by the computed values of enthalpy of formation i.e., -1.46 eV for Cs2CuMoCl6 and -1.33 eV for Cs2CuMoBr6. The bandgap value is noticed as 0.94 and 0.32 eV for Cs2CuMoCl6 and Cs2CuMoBr6, respectively, when calculated using GGA, and this bandgap increased to 2.25 and 0.93 eV when computed using GGA + mBJ. The integration of Hubbard's potential in the range of 1-5 eV further improves their bandgap to 2.38 eV (@1eV) to 2.58 eV (@5eV) for Cs2CuMoCl6 and 0.96 eV (@1eV) to 1.09 eV (@5eV) for Cs2CuMoBr6. The compressive strain consistently reduces the bandgap, whereas tensile strain widens the bandgap till 3 %, which reduces on further increment of tensile strain to 5 % for Cs2CuMoCl6. The Mo magnetic moments and spin magnetization density at iso-value +/- 0.05 e & Aring; slightly vary under strain. The biaxial strain ranging from 0 to 4 % has been employed along with the GGA + mBJ potential to compute the optoelectronic and thermoelectric characteristics, underscoring their potential for transport and energy harvesting implementations.

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