Inhomogeneous Fluctuating Superconductivity Near Room Temperature

Over the past decade, a diverse set of experiments on high-transition temperature ($T_{c})$ cuprate superconductors have produced evidence for the existence of superconducting correlations on short time and/or length scales at temperatures well above the bulk $T_{c}$. This includes the discovery of an unusual magnetic-field induced effect in YBa$_{2}$Cu$_{3}$O$_{y}$ and La$_{2-x}$Sr$_{x}$CuO$_{4}$ above $T_{c}$ using an intense beam of spin-polarized muons at TRIUMF. The measurements show that an externally applied field induces a static internal magnetic field distribution at high temperatures far above $T_{c}$, and that the degree of field inhomogeneity is correlated with the bulk superconductivity that occurs below $T_{c}$. These findings indicate that non-uniform fluctuating superconductivity does survive in some samples at temperatures approaching room temperature. These experiments and the implications for room-temperature superconductivity will be discussed.