First-principles prediction and comprehensive analysis of new spin gapless semiconductors via <i>p</i> -block element substitution in quaternary Heusler compounds: Electronic, thermodynamic, mechanical and dynamical properties

In this paper, we investigate the electronic, magnetic, thermodynamic, dynamical and mechanical properties of a series of quaternary Heusler compounds to identify new spin-gapless semiconductors. Using first-principles calculations, we predict 24 new spin-gapless semiconductors by substituting p-block elements into previously reported quaternary Heusler alloys, and we validate their electronic structures. Their thermodynamic stability is confirmed via formation-energy calculations, with negative formation energies indicating likely experimental feasibility. Calculated mechanical properties and analyses of the elastic constants demonstrate mechanical stability according to the Born stability criteria. The predicted spin-gapless semiconductors obey the Slater–Pauling rule and exhibit integer magnetic moments. Phonon spectra computed along high-symmetry directions show no negative frequencies, indicating dynamical stability of these compounds.