Effect of negative pressure on superconducting transition temperature of MgB2

Atomistic simulation has been performed with interatomic potentials to investigate the effect of negative hydrostatic pressure on the superconducting transition temperature (Tc) of MgB2. The calculation reveals that Tc can be greatly enhanced by applying negative pressure and it can reach up to 52.2 K at −13 GPa, about 13 K higher than that at ambient pressure. The mechanism for the enhancement of Tc is attributed to that negative pressure reduces high-frequency phonon vibrations of B and thus dramatically enhances the electron–phonon coupling. Our result seems to open up a possible way for the enhancement of Tc in MgB2.

Research highlights
► We investigate the effect of negative pressure on Tc of MgB2 by atomistic simulation.
► The simulation reveals that Tc can be greatly enhanced by applying negative pressure.
► At -13 GPa Tc can reach up to 52.2 K, ∼13 K higher than that at ambient pressure.
► We attribute the enhancement to the softening of E2g mode under negative pressure.