• 제목/요약/키워드: intrinsic junctions

검색결과 42건 처리시간 0.029초

Oscillatory Josephson-Vortex Resistance in Stacks of $Bi_{2}Sr_{2}CaCu_{2}O_{8+x}$ Intrinsic Josephson Junctions

  • 최재현;배명호;이후종;김상제
    • Progress in Superconductivity
    • /
    • 제7권1호
    • /
    • pp.17-21
    • /
    • 2005

  • We report the oscillation of the Josephson vortex-flow resistance in the rectangular stacks of $Bi_{2}Sr_{2}CaCu_{2}O_{8+x}$(Bi-2212) intrinsic Josephson junctions (IJJs). Apiece of Bi-2212 single crystal containing a few tens of IJJs was sandwiched between two gold electrodes and fabricated into a rectangular shape with the typical lateral size of about $1.5{\times}10\;{\mu}m^2$, using e-beam lithography and focused ion-beam etching techniques. In a tesla-range magnetic field applied in parallel with the junction planes, the oscillation of the Josephson vortex flow resistance was observed at temperatures near 60 K. The oscillation results from the interplay between the triangular Josephson vortex lattice and the potential barrier at the boundary of a single crystal. The oscillatory magnetoresistance for different bias currents, external magnetic fields, and the tilt-angles provides useful information on the dynamics of the coupled Josephson-vortex lattice system.

  • PDF

$Bi_2Sr_2CaCu_2O_{8+x}$ 단결정 선천성 조셉슨 접합에서의 플럭손 결맞음 운동 (Coherent motion of fluxons in stacked intrinsic Josephson junctions of $Bi_2$$Sr_2$Ca$Cu_2$$O_{8+x}$ single crystals)

  • 도용주;장현식;장동인;이후종;김진희;김규태;이우;최진호
    • Progress in Superconductivity
    • /
    • 제3권1호
    • /
    • pp.28-30
    • /
    • 2001

  • We studied the flux-flow current-voltage characteristics of microwave-generated fluxons formed in serially stacked intrinsic Josephson junctions fabricated on$ HgI_2$-intercalated $Bi_2$$Sr_2$$CaCu_2$O/8+x/(Bi2212) single crystals. With increasing the irradiation power of 73$\square$76 GHz microwave, the supercurrent branch became resistive and split into multiple sub -branches. Each sub-branch represented a specific mode of collective motion of Josephson fluxons. We also observed similar branch splitting In a mesa prepared on an underdoped Bi2212 single crystal in a static magnetic field.

  • PDF

Andreev reflection in the c-axis transport of $Bi_2$$Sr_2$Ca$Cu_2$$O_{8+x}$ single crystals near $T_c$

  • Chang, Hyun-Sik;Lee, Hu-Jong
    • Progress in Superconductivity
    • /
    • 제3권2호
    • /
    • pp.140-145
    • /
    • 2002

  • An enhancement of the c-axis differential conductance around the zero-bias voltage near the superconducting transition temperature $T_{c}$ has been observed in $Au/Bi_2$$Sr_2$$CaCu_2$$O_{8+x}$ junctions. We attribute such an enhancement to the Andreev reflection (AR) between the surface Cu-O bilayer with suppressed superconductivity and the next superconducting Cu-O bilayer. The continuous evolution of the differential conductance, from gap like depression to an AR-like peak structure, around the zero-bias voltage points to weakening of the barrier strength of the nonsuperconducting layer between adjacent Cu-O bilayers as temperature approaches $T_{c}$ from below. The peak structure disappeared just below the bulk $T_{c}$ value of underdoped Bi2212 single crystals, whereas it survived up to ~1 K above $T_{c}$ in Junctions prepared on slightly overdosed crystals. According to a recently proposed theoretical consideration, a wider temperature range of the AR a bone $T_{c}$ is expected in the underdoped regime when phase-incoherent preformed pairs emerge in the pseudogap state. Our result is in contradiction to the preformed pair scenario. scenario.o.

  • PDF

c-axis Tunneling in Intercalated Bi$_2Sr_2CaCu_2O_{8+x}$ Single Crystals

  • Lee, Min-Hyea;Chang, Hyun-Sik;Doh, Yong-Joo;Lee, Hu-Jong;Lee, Woo;Choy, Jin-Ho
    • 한국초전도학회:학술대회논문집
    • /
    • 한국초전도학회 1999년도 High Temperature Superconductivity Vol.IX
    • /
    • pp.260-260
    • /
    • 1999

  • We compared c-axis tunneling characteristics of small stacked intrinsic Josephson junctions prepared on the surface of pristine, I-, and HgI$_2$-intercalated Bi$_2Sr_2CaCu_2O_{8+x}$ (Bi2212) single crystals. The R(T) curves are almost metallic in I-Bi2212 specimens, but semiconducting in HgI$_2$-Bi2212 ones.· The transition temperatures were 82.0 K, 73.0 K, and 76.8 K for pristine Bi2212, I-Bi2212, and HgI2-Bi2212 specimens, respectively, consistent with p-T$_c$ phase diagram. Current-voltage (IV) characteristics of both kinds of specimens show multiple quasiparticle branches with well developed gap features, indicating Josephson coupling is established between neighboring CuO$_2$ planes. The critical current I$_c$ of I-Bi2212 is almost the same as of that of pristine crystals, but I$_c$ is much reduced in Hgl$_2$-Bi2212. In spite of expanded interlayer distances, the interlayer coupling is not significantly affected in I-Bi2212due to holes generated by iodine atoms. The coupling in HgI$_2$-Bi2212 is, however, weakened due to inertness of HgI$_2$ molecules and the expansion of interlayer distance. Relation between the superconducting transition temperature T$_c$ and the critical current I$_c$ seems to contradict Anderson's interlayer-pair-tunneling theory but agree with a modified version of it.

  • PDF