Mechanism of the electric-field effect in the high-Tccuprates

The origin of the large electric field effect in the high-${\mathit{T}}_{\mathit{c}}$ superconductors has been identified by measuring the field effects in ${\mathrm{Bi}}_2$ ${\mathrm{Sr}}_2$ ${\mathrm{CaCu}}_2$ ${\mathrm{O}}_{8+\mathit{x}}$ and comparing them with those in ${\mathrm{YBa}}_2$ ${\mathrm{Cu}}_3$ ${\mathrm{O}}_{7\mathrm{-}\mathit{x}}$. In contrast to the predictions of models based on field-driven oxygen rearrangement, large field effects are observed in the ${\mathrm{Bi}}_2$ ${\mathrm{Sr}}_2$ ${\mathrm{CaCu}}_2$ ${\mathrm{O}}_{8+\mathit{x}}$ system, providing evidence that the effects arise from field-driven movement of the mobile charge carriers in the superconductor and thus are a generic property of the high-${\mathit{T}}_{\mathit{c}}$ compounds.