Destruction of chain-superconductivity in YBa_2Cu_4O_8 in a weak magnetic field
arXiv:1008.3532 · doi:10.1103/PhysRevB.82.140506
Abstract
We report measurements of the temperature dependent components of the magnetic penetration depth λ(T) in single crystal samples of YBa_2Cu_4O_8 using a radio frequency tunnel diode oscillator technique. We observe a downturn in λ(T) at low temperatures for currents flowing along the b and c axes but not along the a axis. The downturn in λ_b is suppressed by a small dc field of ~0.25 T. This and the zero field anisotropy of λ(T) likely result from proximity induced superconducting on the CuO chains, however we also discuss the possibility that a significant part of the anisotropy might originate from the CuO2 planes.
5 pages