Electrostatic modulation of superconductivity in ultrathin GdBa2Cu3O7-x films

The polarization field of the ferroelectric oxide Lead zirconate titanate [ Pb(ZrxTi1-x)O-3] was used to tune the critical temperature of the high-temp erature superconducting cuprate gadolinium barium copper oxide (GdBa2Cu3O7- x) in a reversible, nonvolatile fashion. For slightly underdoped samples, a uniform shift of several Kelvin in the critical temperature was observed, whereas for more underdoped samples, an insulating state was induced. This transition from superconducting to insulating behavior does not involve che mical or crystalline, modification of the material.