Evidence for pressure-induced node-pair annihilation in C d3 A s2

We report a magnetotransport study of Dirac semimetal Cd3As2 under high pressure. The Shubnikov-de Haas oscillations are measured at different pressures to reveal the evolution of the Fermi surface. A sudden change in the phase factor of the oscillations occurs at 1.3 GPa along with the unanticipated shrinkage of the Fermi surface, which is well below the structure transition point from the tetragonal to the monoclinic structure (∼2.5GPa). High-pressure x-ray diffraction also reveals an anisotropic compression of the Cd3As2 lattice around a similar pressure. Through the first-principles calculations, we find that such axial compression along the c direction will shift the Dirac nodes towards the Brillouin zone center and will eventually introduce a finite energy gap. Our result unveils a possible topological phase transition in pressurized Cd3As2 without structure transition.