paper

Superconductivity arising from pressure induced Lifshitz transition in RbPdSe with kagome lattice

arXiv:2203.00493 · doi:10.1103/PhysRevB.106.214501

Abstract

According to the Bardeen-Cooper-Schrieffer (BCS) theory, superconductivity usually needs well defined Fermi surface(s) with strong electron-phonon coupling and moderate quasiparticle density of states (DOS). A kagome lattice can host flat bands and topological Dirac bands; meanwhile, due to the parallel Fermi surfaces and the saddle points, many interesting orders are expected. Here, we report the observation of superconductivity by pressurizing a kagome compound RbPdSe using a DAC anvil. The parent compound shows an insulating behavior; however, it gradually becomes metallic and turns to a superconducting state when a high pressure is applied. High pressure synchrotron measurements show that there is no structural transition occurring during this transition. The density-functional-theory (DFT) calculations illustrate that the insulating behavior of the parent phase is due to the crystalline field splitting of the partial Pd-4d bands and the Se-derivative 4-band. However, the threshold of metallicity and superconductivity are reached when the Lifshitz transition occurs, leading to the emergence of tiny Fermi surface at point. Our results point to an unconventional superconductivity and shed new light on understanding the electronic evolution of a kagome material.

28 pages, 6 figures

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