Effects of a particle-hole asymmetric pseudogap on Bogoliubov quasiparticles

Abstract

We show that in the presence of a pseudogap, the spectral function in the superconducting state of the underdoped cuprates exhibits additional Bogoliubov quasiparticle peaks at both positive and negative energy which are revealed by the particle-hole asymmetry of the pseudogapped energy bands. This provides direct information on the unoccupied band via measurement of the occupied states. When sufficiently close, these Bogoliubov peaks will appear to merge with existing peaks leading to the anomalous observation, seen in experiment, that the carrier spectral density broadens with reduced temperature in the superconducting state. Using the resonating valence bond (RVB) spin liquid model in conjunction with recent angle-resolved photoemission spectroscopy (ARPES) data allows for an empirical determination of the temperature dependence of the pseudogap suggesting that it opens only very gradually below the pseudogap onset temperature $T^*$.