The superconductor-insulator transition (SIT) in high-temperature copper-oxide (‘cuprate’) superconductors is commonly triggered by the application of a magnetic field. However, due to the complexities of superconductivity, many questions are still to be answered about the exact process which underpins the SIT and the associated quantum phases the material undergoes.
Scientists had thought that high-temperature superconductors had a single quantum critical point at which the material switches from a superconductor to an insulator when a particular strength of magnetic field was applied.
Now, an international team of researchers from the USA and Japan, including Takao Sasagawa at Tokyo Institute of Technology, have uncovered a two-stage transition in lanthanum-strontium-copper-oxide high-temperature superconductors (LSCOs), leading to the first complex phase diagram of the behavior of LSCOs.
“The delicate interplay of thermal fluctuations, quantum fluctuations and disorder leads to a complex H-T [magnetic field-temperature] phase diagram of vortex matter,” the authors state in their paper published in Nature Physics.
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