Detection of quantized flux penetration into very small 0-type Josephson linksin Bi2Sr2Ca1Cu2Oy single crystals using ESR spectrometry

Abstract

Magnetic-flux trapping in Bi2Sr2CaCu2Oy single crystals is investigated using an electron-spin-resonance spectrometer to study the trapping mode of high-Tc superconductors. Several series of periodic microwave (MW) absorption spectra were observed at external fluxes Φx=(k±1/2)Φ0,nk=0,1,2,ldots . They are superposed on a broad MW spectrum ascribed to the surface impedance. The periodic spectrum is clear evidence for stepwise transitions (k→k+1) between energy states of Josephson-junction links by microwave absorption and for stepwise penetration of flux quanta Φ0. The periodicity with a half quantum (k±1/2)Φ0 was shown to be due to 0-type Josephson-junction links. It was possible to follow the angular dependence of a few sets of periodic spectra and to determine the sizes and orientations of the intracrystal Josephson links. The link size and the number of quanta penetrating the links are very small, an order of 0.5–4 μm2 and several to a few tens of quanta, and are about 10–102 times smaller than those in Y-Ba-Cu-O and Tl2Ba2CaCu2O8 crystals. Every link surface is found to be closely located in the ab crystal plane.

Source-reported materials — not catalogue approval

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