Berry phase in cuprate superconductors

Abstract

The geometrical Berry phase is widely recognized as having profound implications for the properties of electronic systems. Over the last decade or so, the Berry phase has been essential to our understanding of new materials such as graphene and topological insulators. In general, a nontrivial Berry phase is a result of band crossing as in the case of a massless Dirac point. The Berry phase can be accessed in quantum oscillation measurements as it contributes to the phase mismatch of electrons in their cyclotron orbits. With their enigmatic pseudogap and superconducting phases, the cuprates are materials where the Berry phase is thus far unknown. Based on quantum oscillation data in the high-field normal state of underdoped cuprates, we determined the Berry phase contribution to the phase mismatch unambiguously in this family of materials. In the hole-doped materials YBa2Cu3Oy, YBa2Cu4O8, and HgBa2CuO4+δ, a trivial Berry phase of 0 mod(2π) is systematically observed, while the electron-doped Nd2−xCexCuO4 exhibits a significant nonzero Berry phase of 1.4π. Our results set significant constraints on the microscopic description of the high-field normal state and, in particular, do not support a nodal structure or broken time-reversal symmetry in the hole-doped compounds.

Source-reported materials — not catalogue approval

Similar papers