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

• Published in: npj quantum materials 2017-02, Vol.2 (1), p.1-6, Article 8
• Main Authors: Ramshaw, B. J., Harrison, N., Sebastian, S. E., Ghannadzadeh, S., Modic, K. A., Bonn, D. A., Hardy, W. N., Liang, Ruixing, Goddard, P. A.
• Format: Article
• Language: English
• Subjects: 639/301/119/1003; 639/301/119/995; Anisotropy; Broken symmetry; Condensed Matter Physics; CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; Copper oxides; Cuprates; Fermi surfaces; High Magnetic Field Science; Interlayers; Magnetoresistance; Magnetoresistivity; Physicists; Physics; Physics and Astronomy; Quantum Physics; Room temperature; Structural Materials; Superconductivity; Surfaces and Interfaces; Symmetry; Thin Films; Transition temperature; Unconventional superconductors; YBCO superconductors
• ISSN: 2397-4648; 2397-4648
• DOI: 10.1038/s41535-017-0013-z

Broken fourfold rotational (C 4 ) symmetry is observed in the experimental properties of several classes of unconventional superconductors. It has been proposed that this symmetry breaking is important for superconducting pairing in these materials, but in the high-T c 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-T c ) superconductor YBa 2 Cu 3 O 6.58 , directly revealing broken C 4 symmetry on the Fermi surface. Moreover, we demonstrate that this Fermi surface has C 2 symmetry of the type produced by a uniaxial or anisotropic density-wave phase. This establishes the central role of C 4 symmetry breaking in the Fermi surface reconstruction of YBa 2 Cu 3 O 6+ δ , and suggests a striking degree of universality among unconventional superconductors. Condensed matter physics: Rotational symmetry breaking in unconventional superconductors Observations of broken rotational symmetry in YBa 2 Cu 3 O 6.58 suggest that it could be a universal feature in unconventional superconductors. The origin of superconductivity in materials that do not conform to conventional Bardeen–Cooper–Schrieffer theory remains an important puzzle for condensed matter physicists; one that could hold the key to designing materials that have no resistance near room temperature. An international team of researchers led by Brad Ramshaw used angle-dependent magnetoresistance measurements to directly reveal a broken rotational symmetry on the Fermi surface of underdoped crystals of the copper oxide-based unconventional superconductor YBa 2 Cu 3 O 6.58 . As this feature has been found in several other classes of unconventional superconductors, the authors suggest that this may be a universal feature, which could play an important role in the unconventional formation of superconducting pairs.