Contrasting dynamic spin susceptibility models and their relation to high-temperature superconductivity

Abstract

We compare the normal-state resistivities ρ and the critical temperatures Tc for superconducting dx2−y2 pairing due to antiferromagnetic (AF) spin fluctuation exchange in the context of two phenomenological dynamical spin susceptibility models for the cuprate high-Tc materials, one based on fits to NMR data on Y-Ba-Cu-O (YBCO) proposed by Millis, Monien, and Pines (MMP) and Monthoux and Pines (MP), and the other based on fits to neutron scattering data on YBCO proposed by Radtke, Ullah, Levin, and Norman (RULN). Assuming comparable electronic bandwidths and resistivities in both models, we show that the RULN model gives a much lower d-wave Tc (≲20 K) than the MMP model (with Tc∼100 K). We demonstrate that these profound differences in the Tc’s arise from fundamental differences in the spectral weight distributions of the two model susceptibilities at high (>100 meV) frequencies and are not primarily caused by differences in the calculational techniques employed by MP and RULN. Further neutron scattering experiments, to explore the spectral weight distribution at all wave vectors over a sufficiently large excitation energy range, will thus be of crucial importance to resolve the question whether AF spin fluctuation exchange can provide a viable mechanism to account for high-Tc superconductivity. Limitations of the Migdal-Eliashberg approach in such models will be discussed. © 1996 The American Physical Society.

Source-reported materials — not catalogue approval

Similar papers