Bereiche | Tage | Auswahl | Suche | Downloads | Hilfe

TT: Fachverband Tiefe Temperaturen

TT 10: Superconductivity: Tunneling, Josephson Junctions, SQUIDs

TT 10.3: Vortrag

Montag, 23. März 2009, 14:30–14:45, HSZ 105

Laser imaging of hot spots and waves in Bi₂Sr₂CaCu₂O₈ intrinsic Josephson junctions — •S. Guénon¹, M. Grünzweig¹, H. B. Wang², J. Yuan², A. Iishi², S. Arisawa², T. Hatano², T. Yamashita², D. Koelle¹, and R. Kleiner¹ — ¹Physikalisches Institut & Center for CollectiveQuantum Phenomena, Universität Tübingen, Germany — ²National Institute for Materials Science, Tsukuba3050047, Japan

Motivated by the discovery of coherent Terahertz emission in large sized stacks of Bi₂Sr₂CaCu₂O₈ intrinsic Josephson junctions [1] we used low-temperature scanning laser microscopy (LTSLM) to image local electric field distributions of mesa structures patterned on top of Bi₂Sr₂CaCu₂O₈ single crystals [2]. In LTSLM a laser beam at position (x,y) on the sample surface locally warms up an area of about a few µm². This locally well defined heat distribution changes the electrical properties of the system, which in turn leads to a voltage change Δ V(x,y) measured globally across the sample. The mesas (330µm long and 30–70µm wide) were 1 µm thick and consisted of about 670 junctions. In the low-bias regime we find clear signatures of standing electromagnetic waves that essentially are in agreement with the THz emission data in [1]. At high bias voltages we observe the formation of a hot spot, which at some currents is accompanied by standing wave patterns interacting with the hot spot.

[1] L. Ozyuzer et al., Science 318, 1291 (2007)

[2] H. B. Wang, S. Guénon et al., submitted to Phys. Rev. Lett.;

  arXiv:0807.2749v1 [cond-mat.supr-con]