Observation of microwave induced dc voltages in a YBa2Cu3O7−δ single crystal

Microwave induced dc voltages in a YBa 2 Cu 3 O 7−δ single crystal have been observed along its c -axis with or without a dc bias current by utilizing standing waves near the end of an X-band (8–12 GHz) waveguide. With a dc bias current, the effect is larger when the single crystal is coupled to the maximum of the microwave H-field, suggesting that the induced dc voltages are due to vortes flow. Without a dc bias current, the induced voltages resemble the inverse ac Josephson effect and require the presence of both the E- and H-fields of the microwave. The temperature and the bias current dependences of the induced voltages both show several peak structures indicating the existence of multiple Josephson junctions inside a single crystal sample.