3/2 Fermi liquid: an emergent quantum matter in high Tc cuprates and theory of anomalous quantum oscillations

Full text: Electrical and magnetic properties of under doped cuprates in the spin gap phase, a precursor to high Tc superconducting state, is riddled with puzzles. We propose a novel reference state [1] to study this phase, where each hole dopant adds one real halon and one real spinon, with Haldane exclusion statistics gh =1 and gs = 1/2, to a fairly inert (pseudo gaped) spin liquid vacuum, resulting in a low density spin-charge liquid. Spins and charges interact and form a novel collective state, a 3/2-Fermi liquid. A holon pairs with a spinon; this hole like fermion composite carries charge +e and a spin-half moment and novel exclusion statistics ghole = 3/2. We explain an anomalous expansion of Fermi sea area by 3/2, seen in recent quantum oscillation experiments [2,3] at two different dopings. We also discuss how i) high Tc superconductivity arises from the 3/2 Fermi liquid, as a cooperative spinon pair condensation and ii) the system changes to a large Fermi sea through a quantum phase transition at T=0. (authors)