Abstract:
Resonating valence bond states, in addition to being seats of high Tc superconductivity, are seats of unusual metallic states. Under doped pseudo gap phase and optimally doped metallic phase of high Tc cuprates exemplify this. We show that, generically, lightly doped RVB states become, what we define as an Anderson-Haldane (AH) liquid, where the doped holes have an unconventional (Haldane) exclusion statistics of 3/2. That is, in certain RVB background the doped physical hole (charge +e and spin-half) is a weakly bound (spin-charge locked, in the sense of Anderson) composite of a holon and a spinon. It has an exclusion statistics of 3/2 = 1 + 1/2, a sum of exclusion statistics of holon and a spinon. Consequently each doped hole, a fermion, occupies 3/2 of k-space volume than that occupied by an usual fermionic hole in a band insulator. AH liquid behaves like a fermi liquid for all practical purposes. However it violates Luttinger theorem and volume of fermi surface is determined by Haldane exclusion statistics parameter and hole density. Further, its shape is determined mostly by super exchange interactions. Issue of superconductivity, large fermi surface and connection of our work to an RVB based theory of Yang, Rice and Zhang will be discussed.
Coffee and tea will be served 20 minutes prior to the seminar