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Research Team Led by Cao Guanghan Discovers Superconductivity in Quasi-One-Dimensional K2Cr3As3

[From]:浙江大学[Editor]:[Date]:2015/04/10[Hits]:9

 
Explorations of novel superconductors have been at the forefront of over 100 years of superconductivity research. The discovery of high-temperature superconductivity in quasi-two-dimensional copper oxides in the 1980s led to a paradigm that quasi-two-dimensional systems with strongly correlated electrons may host unconventional superconductivity. Indeed, unconventional superconductivity has been discovered in a few classes of layered materials containing d-block elements, such as iron pnictides. Observations of superconductivity in quasi-one-dimensional materials with strongly interacting electrons, however, are rare and are of great interest given the relative simplicity of one dimension.

The research team led by Cao Guanghan from the Department of Physics, Zhejiang University, discovers bulk superconductivity at 6.1 K in an alkali-metal chromium pnictide, K2Cr3As3, with significant electron correlations. The crystalline structure of this material contains quasi-one-dimensional double-walled subnanotubes (about 0.58 nm in outer diameter) with face-sharing octahedron linear chains in the inner and outer walls. The material indeed bears significantly strong electron correlations, as manifested by a large electronic specific-heat coefficient. Researchers also observe sharp superconductivity transitions at 6.1 K, below which resistivity drops to zero, the external magnetic field is expelled, and the specific heat shows a jump. Furthermore, the signature of non-Fermi liquid appears as a linear temperature dependence of resistivity in a broad temperature range (7–300 K). Unconventional superconductivity is additionally evident based on the high upper critical field exceeding the Pauli limit. It is expected that the findings will additionally expand research domains in quasi-one-dimensional physics and unconventional superconductivity.

The results have been published online in Physical Review X. The research is funded by the National Natural Science Foundation of China, the 973 Project of China’s Ministry of Science and Technology and the Basic Research & Development Fund of China’s Ministry of Education.