Advances in Cryogenic Engineering *Materials*
pp 1039-1048 |
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# Current-Voltage Characteristics of Bi_{2}Sr_{2}CaCu_{2}O_{8+δ} in the C-Axis Direction

## Abstract

Current-voltage (*I-V*) characteristics of Bi_{2}Sr_{2}CaCu_{2}O_{8+δ} single crystals were measured in the *c*-axis direction as a function of temperature and magnetic field parallel to the current. In order to eliminate heating effect, a voltage pulse with a width of 0.5 – 1 μs was applied for each *I-V* point. We found an ohmic region far below the gap voltage. The ohmic resistance increased with decreasing temperature and grew 30 times larger at 4.2 K than that at room temperature. Magnetic field strongly suppressed the critical current but did not change this ohmic resistance. These behaviors can be explained by a semiconductive shunt resistance connected in parallel to a stack of Josephson junctions. By applying two-step voltage pulses, we observed a hysteretic feature of the intrinsic Josephson junctions. Crystals with different oxygen contents showed a large variation in critical current, normal resistance, the shunt resistance at low temperature and the degree of hysteresis due to a difference in anisotropy ratios. Utilizing the bistability revealed by the hysteretic feature, the Bi2212 crystal can function as a switching device in the *c*-direction. A natural stack of many junctions will exhibit large response voltage, which is a great advantage for application to power devices.

## Keywords

Contact Resistance Josephson Junction Anisotropy Ratio Response Voltage Shunt Resistance## Preview

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