Exploring the thermoelectric and magnetic properties of uranium selenides: Tl2Ag2USe4 and Tl3Cu4USe6

• Electronic, magnetic and thermoelectric properties of uranium selenides are investigated with DFT.
• They show a narrow direct energy band gap of 0.7 and 0.875 eV.
• U-d/f states are responsible for electrical transport properties.
• Tl3Cu4USe6 is more suitable for thermoelectric device applications than Tl2Ag2USe4.

The electronic, magnetic and thermoelectric properties of Tl2Ag2USe4 and Tl3Cu4USe6 compounds were investigated using the full potential linear augmented plane wave (FP-LAPW) method based on the density functional theory (DFT). The exchange correlation was treated with the generalized gradient approximation plus optimized effective Hubbard parameter and spin–orbit coupling (GGA+U+SOC). The present uranium selenides show narrow direct energy band gap values of 0.7 and 0.875 eV for Tl2Ag2USe4 and Tl3Cu4USe6 respectively. For both selenides U-d/f states are responsible for electrical transport properties. Uranium atoms were the most contributors in the magnetic moment compared to other atoms and show ferromagnetic nature. The spin density isosurfaces show the polarization of neighboring atoms of Uranium, such as silver/copper and selenium. Thermoelectric calculations reveal that Tl3Cu4USe6 is more suitable for thermoelectric device applications than Tl2Ag2USe4.

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