Anomalous noise in the pseudogap regime of YBa2Cu3O(7-delta).

An unusual noise component is found near and below about 250 K in the normal state of underdoped YBCO and Ca-YBCO films. This noise regime, unlike the more typical noise above 250 K, has features expected for a symmetry-breaking collective electronic state. These include large individual fluctuators, a magnetic sensitivity, and aging effects. A possible interpretation in terms of fluctuating charge nematic order is presented.

Electronic transport in underdoped YBa2Cu3O7-delta nanowires: evidence for fluctuating domain structures.

We have measured the transport properties of a series of underdoped YBa(2)Cu(3)O(7-delta) nanowires fabricated with widths of 100-250 nm. We observe large telegraphlike fluctuations in the resistance between the pseudogap temperature T* and the superconducting transition temperature T(c), consistent with the formation and dynamics of a domain structure. We also find anomalous hysteretic steps in the current-voltage characteristics well below T(c).