Magnetic-field-induced uniaxial resistivity in a high-Tc superconductor

Theory suggests that it is impossible for a homogeneous three-dimensional crystal to exhibit superconducting order in two directions but not in the third, especially in the presence of a transverse magnetic field. Here we present experimental evidence for just such a phase. La(1.905)Ba(0.095)CuO(4) is a layered superconductor with a transition temperature, Tc, of 32 K. We show that a perpendicular magnetic field can induce a phase in which zero resistivity is observed parallel to the layers but application of a finite measurement current perpendicular to the layers results in a finite resistivity. Features that stabilize this phase include a crystal symmetry that weakly pins charge and spin stripe order in zero field and the enhancement of stripe order by a perpendicular magnetic field, as we show with diffraction measurements. Analysis of these results provides a new perspective on how superconducting order in underdoped cuprates is limited by fluctuations in the phase of the superconducting order parameter.