Study of Magnetic, Optical, Electronic and Thermodynamic Effects in Thallium Rare Earth Disulphides (TlRES2, RE= Tb- Er)

Abstract

In the present research work, we have investigated density of electronic states, electronic band structure, magnetic structure, optical spectra and temperature dependent thermodynamic characteristics of thallium rare earth sulphides, TlRES₂ (RE: Tb-Er) using FP-LAPW method and PBE-GGA exchange correlation within DFT. The electronic structure pointed out that TlRES₂ compounds show half metallic character. The magnetic moment and spin polarization calculations prove that TlRES₂ are fully spin polarized compounds with ferromagnetic nature. Optical spectra show that intraband transitions occur in infrared (IR) regime due to half metallic character of TlRES₂ and behave as opaque in ultraviolet (UV) region. High refractive index in IR regime also show metallic character and high peak in UV regime show slow propagation of light in UV regime. The reflection coefficient is found maximum (~50–60%) in UV regime. Greater energy loss has been seen on the higher energy side, which corresponds to the stimulation of plasmons by electrons moving through the compounds. Plasma resonances lead to the frequent peaks at ~ 6.0 eV, 11.0 eV, and 12.0 eV. According to calculations made using the quasi-harmonic Debye model, TlRES₂ compounds are dimensionally less stable (i.e., much hard), have poor thermal conductivity, and experience faster-than-average disorder with increasing the temperature.