Universality in Cuprates: A Gauge Approach

In high- T c cuprates, many quantities exhibit a non-Fermi liquid universality hinting at a very peculiar structure of the underlying pairing mechanism for superconductivity: in this work, we focus on the universality for the in-plane resistivity and the superfluid density. We outline the previously developed spin–charge gauge approach to superconductivity in hole-doped cuprates: we decompose the hole of the t - t ′ - J model for the Cu O 2 planes as the product of a spinful, chargeless gapped spinon and a spinless, charged holon with Fermi surface. Each one of these particle excitations is bound to a statistical gauge flux, allowing one to optimize their statistics. We show that this model allows for a natural interpretation of the universality: within this approach, under suitable conditions, the spinonic and holonic contributions to a response function sum up according to the Ioffe–Larkin rule. We argue that, if the spinonic contribution dominates, then one should expect strongly non-Fermi-liquid-like universality, due to the insensitivity of spinons to Fermi surface details. The in-plane resistivity and superfluid density are indeed dominated by spinons in the underdoped region. We theoretically derive these quantities, discussing their universal behaviours and comparing them with experimental data.