Continuous doping of a cuprate surface: new insights from in-situ ARPES

TL;DR

This study introduces a new in-situ doping technique for cuprate surfaces, enabling detailed ARPES measurements across doping levels, revealing a linear relationship between the quasiparticle gap and Nernst temperature, and providing insights into superconducting pairing and pseudogap phenomena.

Contribution

The paper presents a novel ozone/vacuum annealing method for continuous surface doping of cuprates, allowing precise ARPES analysis over a wide doping range, which advances understanding of superconducting and pseudogap behaviors.

Findings

Quasiparticle d-wave gap is linearly proportional to Nernst temperature.

Superconducting pairing emergence coincides with free vortex onset.

Provides detailed doping-dependent energy gap and spectral weight data.

Abstract

The cuprate superconductors distinguish themselves from the conventional superconductors in that a small variation in the carrier doping can significantly change the superconducting transition temperature (T_c), giving rise to a superconducting dome where a pseudogap (ref. 1,2) emerges in the underdoped region and a Fermi liquid appears in the overdoped region. Thus a systematic study of the properties over a wide doping range is critical for understanding the superconducting mechanism. Here, we report a new technique to continuously dope the surface of Bi2Sr2CaCu2O8+x through an ozone/vacuum annealing method. Using in-situ ARPES, we obtain precise quantities of energy gaps and the coherent spectral weight over a wide range of doping. We discover that the d-wave component of the quasiparticle gap is linearly proportional to the Nernst temperature that is the onset of superconducting vortices (ref. 3), strongly suggesting that the emergence of superconducting pairing is concomitant with the onset of free vortices, with direct implications for the onset of superconducting phase coherence at T_c and the nature of the pseudogap phenomena.