Evidence of hole-electron quasiparticle interference in ErSi2 semimetal by Fourier-transform scanning tunneling spectroscopy.

The semimetallic ErSi2 layer grown on Si(111) substrates provides an ideally confined 2D electron and hole gas that reflects in complex standing wave pattern at 77 K. The quasiparticles exist in a wide energy range from -800 to 300 meV without mixing with silicon bulk excitations. By comparing high resolution Fourier transform of dI/dV maps, with joint density of states calculations, we are able to determine the 2D band structure. We also clearly demonstrate that hole-hole and hole-electron quantum interferences dominate over electron-electron ones.