Physical Review B - CMMP

Paramagnetic effect in YBa2Cu3O7-x grain-boundary junctions

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A detailed investigation of the magnetic response of YBa2Cu 3Ox grain-boundary Josephson junctions has been carried out using both radio-frequency measurements and scanning superconducting quantum interference device microscopy. In a nominally zero-field-cooled regime we observed a paramagnetic response at low external fields for 45° asymmetric grain boundaries. We argue that the observed phenomenology results from the d-wave order-parameter symmetry and depends on Andreev bound states.