Data for Broken rotational symmetry on the Fermi surface of a high-Tc superconductor

It has been proposed that this symmetry breaking is important for superconducting pairing in these materials, but in the high-Tc cuprates this broken symmetry has never been observed on the Fermi surface. Here we report a pronounced anisotropy in the angle dependence of the interlayer magnetoresistance of the underdoped high transition temperature (high-Tc) superconductor YBa2Cu3O6.58, directly revealing broken C4 symmetry on the Fermi surface.

Moreover, we demonstrate that this Fermi surface has C2 symmetry of the type produced by a uniaxial or anisotropic density-wave phase. This establishes the central role of C4 symmetry breaking in the Fermi surface reconstruction of YBa2Cu3O6+δ , and suggests a striking degree of universality among unconventional superconductors.<br><br>YBCO58_4p2K_phi0 YBCO58_4p2K_phi15 YBCO58_4p2K_phi30 YBCO58_4p2K_phi45 YBCO58_4p2K_phi60 YBCO58_4p2K_phi75 YBCO58_4p2K_phi90 YBCO58_4p2K_phi105 YBCO58_4p2K_phi120 YBCO58_4p2K_phi135 YBCO58_4p2K_phi150 YBCO58_4p2K_phi165 YBCO58_4p2K_phi180 YBCO58_15K_phi0 YBCO58_15K_phi15 YBCO58_15K_phi30 YBCO58_15K_phi45 YBCO58_15K_phi60 YBCO58_15K_phi75 YBCO58_15K_phi90