Spectroscopic signatures of high−Tc superconductivity and strange metallicity in overdoped Bi2201

Abstract

In this work, the overdoped strange metal regime of the single-layer cuprate Bi2201 superconductor is investigated via three distinct spectroscopic probes – angle-resolved photoemission (ARPES), electronic Raman scattering (ERS), and muon spin rotation (µSR) spectroscopy – across a range of doping levels which span this full regime from just beyond p* to the edge of the superconducting dome.

ARPES and ERS extract an inelastic scattering rate that is weakly anisotropic and consistent with Planckian dissipation (ℏ/τ ≈kBT) across accessible Fermi surface sectors even as Tc collapses, with no systematic doping dependence – despite the marked decrease in the T-linear resistivity coefficient seen in transport. µSR reveals a monotonic loss of the zero-temperature in-plane inverse-squared penetration depth, which is proportional to the superfluid density, ns(0), over the effective mass, m* - and since ARPES shows no strong enhancement of m* with increased hole-doping, this indicates that the collapse in Tc appears to be dominated by depletion of the superfluid density, ns(0).

In parallel, the dominant nodal–antinodal dichotomy beyond p∗is governed primarily by a strongly momentum- and doping-dependent redistribution and recovery of (coherent) low-energy spectral
weight with overdoping as the condensate diminishes. These results place important constraints on theoretical descriptions of the overdoped cuprate strange metal phase. Viable theroetical frameworks should accommodate near-Planckian, weakly anisotropic inelastic scattering that shows no clear trend in doping, together with a condensate collapse chiefly driven by ns(0) and the evolution of low-energy spectral weight.

This work strongly motivates an extension of the ARPES and ERS studies performed here, deep into the heavily overdoped regime (alongside Hall effect measurements) to determine if and where coherence saturates, and whether true Fermi-liquid quasiparticle characteristics are recovered.

Date of Award	6 Feb 2026
Original language	English
Awarding Institution	University of Bristol
Sponsors	European Research Council
Supervisor	Nigel E Hussey (Supervisor) & Stephen B Dugdale (Supervisor)