Temperature dependence of the penetration depth in YBa2Cu3O7-delta measured by microwave ring resonators

Abstract

YBa2Cu3O7-(TM) (YBCO)) superconducting ring resonators with a YBCO ground plane were fabricated using double-side YBCO films deposited on LaAlO3 (LAO) substrates. The temperature dependent London penetration depth, Delta lambda = lambda (T)-lambda (5K), was systematically studied by varying the oxygen content of the same resonator structure. For fully oxygenated condition (delta = 0.05), the resonator exhibits a quality factor Q > 10(4) at 16K, and Delta lambda (T) displays a linear behavior over a wide range of temperatures. With increasing delta (e.g. delta = 0.2), although Delta lambda is still linear in temperature, the slope changes by more than a factor of 2. As delta is further increased, Delta lambda (T) changes fi om T- to T-2-dependence. The results suggest that in the underdoped regime, the incoherent scattering of charged carriers may become increasingly prominent.