• ZB Su

      Articles written in Pramana – Journal of Physics

    • Metal-insulator crossover in high Tc cuprates: A gauge field approach

      PA Marchetti ZB Su L Yu

      More Details Abstract Fulltext PDF

      A metal-insulator crossover appears in the experimental data for in-plane resistivity of underdoped cuprates and a range of superconducting cuprates in the presence of a strong magnetic field suppressing superconductivity. We propose an explanation for this phenomenon based on a gauge field theory approach to the t-J model. In this approach, based on a formal spin-charge separation, the low energy effective action describes gapful spinons (with a theoretically derived doping dependence of the gap ms2δ¦ ln δ¦) and holons with finite Fermi surface (ɛF ∼ ) interacting via a gauge field whose basic effect on the spinons is to bind them into overdamped spin waves, shifting their gap by a damping term linear in T, which causes the metal-insulator crossover. The presence of a magnetic field perpendicular to the plane acts by increasing the damping, in turn producing a big positive transverse in-plane magnetoresistance at low T, as experimentally observed.

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