ENGINEERING TECHNOLOGY

Progress has been made in the study of pressure regulation of charge density wave materials


Recently, the low-power quantum materials research team of the High Magnetic Field Science Center of the Hefei Institute of Physical Sciences, Chinese Academy of Sciences, cooperated with Anhui University to discover pressure-induced new CDW states and superconductivity in quasi-one-dimensional charge density wave (CDW) materials (CuTe) using diamond top anvil technology, combined with extremely low temperature electrical transport and variable temperature Raman measurement. The results were published in Matter.

The relationship between superconductivity and CDW has always been a hot spot in condensed matter physics. Under the traditional Bardeen-Cooper-Schrieffer (BCS) theory, the two compete for free carriers near the Fermi surface, two competing electron states. In actual materials, when the CDW state is suppressed by pressure or chemical doping, the CDW and superconductivity also show complex relationships such as coexistence and synergy. At the same time, in the copper oxide high-temperature superconductor and the cage superconductor CsV3Sb5, their superconductivity is intertwined with the multiple CDW state.

The team selected CuTe, a quasi-one-dimensional CDW material with a layered structure, as the research object, and further used extremely low temperature and high voltage electric transport and variable temperature and high pressure Raman measurement methods on the basis of previous research to find that pressure can effectively inhibit the initial CDW state (CDW1) in CuTe and induce superconductivity. At about 6.5 GPa, CDW1 transitions to a new CDW state (CDW2), and the transition temperature of CDW2 increases significantly compared to CDW1. With the transition from CDW1 to CDW2, pressure-induced dome-like superconducting phase diagrams appear and exhibit abnormal superconducting broadening. Theoretical calculations show that CDW1 originates from the Fermi surface nesting effect, while CDW2 is driven by electron-inter-electron correlation. The above experiments reveal the novel electron correlation effect in CuTe under high pressure, which provides an ideal platform for exploring the complex interaction between superconductivity and multiple CDW.

The research work is supported by the National Key Research and Development Program of China and the National Natural Science Foundation of China. (Source: Hefei Institute of Physical Sciences, Chinese Academy of Sciences)

Related paper information:https://doi.org/10.1016/j.matt.2023.07.018

Temperature-pressure phase diagram of CuTe

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