Quantum Geometric Contributions to the BKT Transition: Beyond Mean Field Theory
| Autor: | Gaurav Chaudhary, Zhiqiang Wang, Kathryn Levin, Qijin Chen |
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| Rok vydání: | 2020 |
| Předmět: |
FOS: Physical sciences
02 engineering and technology 01 natural sciences Superconductivity (cond-mat.supr-con) Condensed Matter - Strongly Correlated Electrons Effective mass (solid-state physics) Quantum mechanics Condensed Matter::Superconductivity 0103 physical sciences Mesoscale and Nanoscale Physics (cond-mat.mes-hall) 010306 general physics Quantum Superconductivity Physics Condensed Matter::Quantum Gases Quantum geometry Condensed Matter - Mesoscale and Nanoscale Physics Strongly Correlated Electrons (cond-mat.str-el) Condensed Matter - Superconductivity BCS theory 021001 nanoscience & nanotechnology Mean field theory Quantum Gases (cond-mat.quant-gas) Pairing 0210 nano-technology Pseudogap Condensed Matter - Quantum Gases |
| DOI: | 10.48550/arxiv.2007.15028 |
| Popis: | We study quantum geometric contributions to the Berezinskii-Kosterlitz-Thouless (BKT) transition temperature, $T_{\mathrm{BKT}}$, in the presence of fluctuations beyond BCS theory. Because quantum geometric effects become progressively more important with stronger pairing attraction, a full understanding of 2D multi-orbital superconductivity requires the incorporation of preformed pairs. We find it is through the effective mass of these pairs that quantum geometry enters the theory and this suggests that the quantum geometric effects are present in the non-superconducting pseudogap phase as well. Increasing these geometric contributions tends to raise $T_{\mathrm{BKT}}$ which then competes with fluctuation effects that generally depress it. We argue that a way to physically quantify the magnitude of these geometric terms is in terms of the ratio of the pairing onset temperature $T^*$ to $T_{\mathrm{BKT}}$. Our paper calls attention to an experimental study demonstrating how both temperatures and, thus, their ratio may be currently accessible. They can be extracted from the same voltage-current measurements which are generally used to establish BKT physics. We use these observations to provide rough preliminary estimates of the magnitude of the geometric contributions in, for example, magic angle twisted bilayer graphene. Comment: 15 pages, 7 figures; published version |
| Databáze: | OpenAIRE |
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