Study of noise spectroscopy in (Bi, Pb)ィイD22ィエD2SrィイD22ィエD2CaCuィイD22ィエD2OィイD2yィエD2 intrinsic Josephson junctions

Mesa structure，which is produced from highly anisotropic Bi i D22个D 2 Sr锡D22个D 2 CaCu锡D22个D 2 O个D 2 x个D 2(BSCCO)single crystal，shows the Josephson effect in c-direction.Many researchers have discussed the transport mechanism of this intrinsic Josephson junction and claimed that low temperature the stack of SIS(Superconductor/Insulator/Superconductor)Josephson tunnel junctions is naturally formed along the c-axis in the mesa。One of the important and useful spectroscopic tools for a better understanding of the transport mechanism of high-Tc superconductors is low-frequency noise property.Han et al.Have examined the 1/f noise power spectral density for BSCCO single crystals as a function of magnetic field，and temperature。They have widely discussed the physical origin of low frequency voltage noise phenomena in BSCCO single crystal near the superconducting transition point.For high-Tc BSCCO mesas，however，experimental study on the noise characteristics has not yet been reported.We have measured low frequency voltage noise properties across mesa stacks of intrinsic Josephson junctions in Bi y D22 I D 2 Sr I D 22 ii CaCu I D 22 I D 2 O I D 2 x I D 2(BSCCO)single crystals as a function of bias voltage.The mesas were fabricated on the surface of cleaved BSCCO single crystals using standard photolithography and Ar ion-milling techniques.For the current-voltage(I-V)curve，increasing the bias current beyond the critical current I ei D2c文件D2 leads to several finite voltage jump。Ramping the bias current up and down repeatedly yields many discrete branches of the I-V characteristics.The I-I D2c-e D2 of the surface junction in the mesa approximately equals to those of inner junctions.The magnitude of the 1/f noise spectral density was found to increase monotonically with the branch number at fixed bias current。No anomalously enhanced l/f noise was observed.

Mesa structure, which is produced from highly anisotropic BiィイD22ィエD2SrィイD22ィエD2CaCuィイD22ィエD2OィイD2xィエD2 (BSCCO) single crystal, shows the Josephson effect in c-direction. Many researchers have discussed the transport mechanism of this intrinsic Josephson junction and claimed that at low temperature the stack of SIS (Superconductor/Insulator/Superconductor) Josephson tunnel junctions is naturally formed along the c-axis in the mesa. One of the important and useful spectroscopic tools for a better understanding of the transport mechanism of high-Tc superconductors is low-frequency noise property. Han et al. have examined the 1/f noise power spectral density for BSCCO single crystals as a function of magnetic field, and temperature. They have widely discussed the physical origin of low frequency voltage noise phenomena in BSCCO single crystal near the superconducting transition point. For high-Tc BSCCO mesas, however, experimental study on the noise characteristics has not yet been reported.We have measured low frequency voltage noise properties across mesa stacks of intrinsic Josephson junctions in BiィイD22ィエD2SrィイD22ィエD2CaCuィイD22ィエD2OィイD2xィエD2 (BSCCO) single crystals as a function of bias voltage. The mesas were fabricated on the surface of cleaved BSCCO single crystals using standard photolithography and Ar ion-milling techniques. For the current-voltage (I-V) curve, increasing the bias current beyond the critical current IィイD2cィエD2 leads to several finite voltage jump. Ramping the bias current up and down repeatedly yields many discrete branches of the I-V characteristics. The IィイD2cィエD2 of the surface junction in the mesa approximately equals to those of inner junctions. The magnitude of the 1/f noise spectral density was found to increase monotonically with the branch number at fixed bias current. No anomalously enhanced l/f noise was observed.