The discovery of materials with high critical temperature (Tc) remains a pivotal challenge in condensed matter physics. Through systematic structural searches of the Li–Al–H system at 200 GPa, two stable phases, Pm3−m Li3AlH4 and P4/mmm LiAlH5, were predicted, both exhibiting metallic characteristics. Computational results indicate that the electron–phonon coupling (EPC) in Li3AlH4 is primarily dominated by medium-high frequency phonons associated with Li/H atoms, whereas in LiAlH5, it is mainly governed by high-frequency phonons related to H atoms. Within the pressure range of 100–350 GPa, the Tc of these two phases exhibit entirely opposite trends: Li3AlH4 reaches 78.32 K at 350 GPa, while that of LiAlH5 reaches as high as 128.96 K at 100 GPa. This phenomenon primarily arises from the distinct responses of the electronic density of states at the Fermi level (N(EF)) to applied pressure, which directly modulates the EPC strength. Therefore, pressure can regulate the superconducting properties of materials by tuning the coupling between N(EF) and phonons. This study provides a novel strategy for designing high-Tc superconductors and deepens the understanding of the superconducting physical mechanisms in hydrides.
Zhang et al. (Thu,) studied this question.