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Enhancement of Seebeck coefficient with full spin polarization of CsMgN2 Thin Films: A DFT Study



Structural, electronic, and thermoelectric properties of the CsMgN2 compound with its thin film films of Cs-Mg and Mg-N terminations have been studied in a First-Principles study. The total energy changes (E-V) versus the unit cell volume of bulk show better stability in the ferromagnetic than the non-magnetic phase. The E-V diagrams of film Cs-Mg and Mg-N terminations have the ground state points at the ferromagnetic phase. The derivative bulk modulus of Cs-Mg termination is like the bulk phase, which refers to the ionic bonds between atoms.

The magnetic moment of the bulk and two mentioned terminations have the integers of 3µB, 10 µB, and 13 µB, respectively. The DOS and bandstructure diagrams by the mBJ and GGA approximations confirm the half-metallic behavior of the bulk and the mentioned terminations. The energy gaps of their semiconductor phase are 1.40eV, 0.64eV, and 0.20eV, for the bulk, Cs-Mg, and Mg-N terminations, respectively. The Seebeck coefficient of Cs-Mg termination in 200K temperature is much higher than the bulk case. The merit figure of coefficient (ZT) shows that bulk and mentioned terminations have high thermoelectric quality at up spin.

Graphical Abstract