Pseudosuperconductivity

Pseudosuperconductivity is a term used in theoretical discussions and some experimental reports to describe a transport regime in certain materials in which electrical resistance becomes extremely small and phase coherence features resemble those of superconductors, yet the state does not satisfy all the conventional criteria for superconductivity. In practice, pseudosuperconductivity often occurs only over limited length scales, temperature ranges, or in the presence of external fields, and may not extend to a bulk, fully zero-resistance state.

Experimental signatures typically include a large drop in resistivity upon cooling, non-Ohmic current-voltage behavior with a finite apparent critical current, and partial magnetic responses that mimic the Meissner effect but vanish under modest fields or temperatures. Frequency-dependent transport and noise measurements can reveal that the coherence is dynamic or percolative rather than bulk-like.

Several mechanisms have been proposed to account for pseudosuperconductivity. Percolation of superconducting filaments in a non-superconducting matrix can yield near-zero resistance along certain pathways. Proximity-induced superconductivity at interfaces or within granular networks can produce short-range coherence. In two-dimensional systems, phase fluctuations and vortex dynamics may give transient coherence without full bulk superconductivity.

Candidate materials and platforms include ultrathin films near the superconducting threshold, oxide interfaces such as certain LAO/STO heterostructures, and layered or graphene-based systems where superconducting domains are separated by non-superconducting regions. The concept is still debated, and researchers emphasize distinguishing pseudosuperconductivity from true superconductivity through comprehensive transport, magnetic, and spectroscopic tests.