Stability of nodal quasiparticles in underdoped YBa2Cu3O6 y probed by penetration depth and microwave spectroscopy

作者：Huttema W A^*; Bobowski J S; Turner P J; Liang Ruixing; Hardy W N; Bonn D A; Broun D M

来源：Physical Review B, 2009, 80(10): 104509.

DOI：10.1103/PhysRevB.80.104509

High-resolution measurements of superfluid density rho(s)(T) and broadband quasiparticle conductivity sigma(1)(Omega) have been used to probe the low-energy excitation spectrum of nodal quasiparticles in underdoped YBa2Cu3O6 y. Penetration depth lambda(T) is measured to temperatures as low as 0.05 K. sigma 1(Omega) is measured from 0.1 to 20 GHz and is a direct probe of zero-energy quasiparticles. The data are compared with predictions for a number of theoretical scenarios that compete with or otherwise modify pure d(x2-y2) superconductivity, in particular, commensurate and incommensurate spin and charge-density waves; d(x2-y2) is and d(x2-y2) id(xy) superconductivity; circulating current phases; and the BCS-BEC crossover. We conclude that the data are consistent with a pure d(x2-y2) state in the presence of a small amount of strong scattering disorder, and are able to rule out most candidate competing states either completely or to a level set by the energy scale of the disorder, T-d similar to 4 K. Commensurate spin and charge-density orders, however, are not expected to alter the nodal spectrum and therefore cannot be excluded.

• 出版日期2009-9