Evidence Accumulates for Unusual Behavior in Underdoped High‐ $T_{c}$ Superconductors

JUN 01, 1996

The energy gap that conventionally heralds the onset of a superconducting state has been seen in materials well above the temperatures at which they actually become superconducting.

DOI: 10.1063/1.2807647

Barbara Goss Levi

As you cool a conventional superconductor, it acts as a metal until it reaches the critical temperature $T_{c},$ below which it rapidly goes superconducting. But some of the high‐temperature, copper oxide materials—in particular, the underdoped ones, whose densities of charge carriers are below that which gives the highest $T_{c}$ —seem to be preparing for the transition to a superconducting state well before they reach $T_{c} .$ Experiment after experiment on underdoped materials at temperatures above $T_{c}$ has revealed some kind of crossover or change in behavior, which some feel is related to the eventual onset of superconductivity at lower temperatures. When the temperature does reach $T_{c},$ the material goes superconducting, but some of its properties exhibit relatively little additional discontinuity in behavior.

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Evidence Accumulates for Unusual Behavior in Underdoped High‐Tc Superconductors

Evidence Accumulates for Unusual Behavior in Underdoped High‐ $T_{c}$ Superconductors