Electron Tunneling into Single Crystals of YBa2Cu3O7-δ

1989 ◽  
Vol 169 ◽  
Author(s):  
J. M. Valles ◽  
M. Gurvitch ◽  
M. Cucolo ◽  
R. C. Dynes ◽  
J. P. Garno ◽  
...  
Keyword(s):  
Critical Temperature ◽  
Single Crystals ◽  
Linear Dependence ◽  
Tunnel Junctions ◽  
Electron Tunneling ◽  
Additional Structure ◽  
Zero Bias ◽  
Zero Bias Conductance

AbstractWe have fabricated tunnel junctions between chemically etched single crystals of YBa2Cu3O7-δ and evaporated metal counterelectrodes which exhibit reproducible characteristics. Above the bulk critical temperature of YBa2Cu3O7-δ, Tc, the conductance, G(V), has a linear dependence with voltage and has some asymmetry. Below Tc, additional structure associated with the superconductivity appears in G(V). At T>>Tc there is a reproducible finite zero bias conductance.

Zero Bias Conductance Peak Enhancement in Bi 2Sr 2CaCu 2O 8+δ-SiO-Ag Planar Tunnel Junctions

2000 ◽  
Vol 69 (9) ◽  
pp. 2743-2746 ◽  
Author(s):  
Iduru Shigeta ◽  
Toll Uchida ◽  
Yukihiro Tominari ◽  
Takeshi Arai ◽  
Fusao Ichikawa ◽  
...  
Keyword(s):  
Tunnel Junctions ◽  
Zero Bias ◽  
Conductance Peak ◽  
Peak Enhancement ◽  
Zero Bias Conductance

d-Wave Tunnel Junctions

1999 ◽  
Vol 13 (09n10) ◽  
pp. 1295-1299
Author(s):  
A. M. Cucolo ◽  
M. Cuoco ◽  
C. Noce
Keyword(s):  
Weak Coupling ◽  
Tunnel Junctions ◽  
Coupling Model ◽  
Normal Metal ◽  
Tunneling Conductance ◽  
Spin States ◽  
S Wave ◽  
Zero Bias ◽  
Zero Bias Conductance ◽  
D Wave

We study the tunneling spectra for superconductor-insulator-normal metal (S-I-N) tunnel junctions with an s -wave or a d -wave superconductor within the weak-coupling model. We deduce the temperature behavior of tunneling conductance and their peak positions as well as of the zero-bias conductance. The results obtained allow us to discriminate among the two singlet spin states.

scholarly journals Point-contact Andreev reflection spectroscopy on Bi2Se3 single crystals

2016 ◽  
Vol 30 (13) ◽  
pp. 1642002 ◽  
Author(s):  
C. R. Granstrom ◽  
I. Fridman ◽  
H.-C. Lei ◽  
C. Petrovic ◽  
J. Y. T. Wei
Keyword(s):  
Single Crystals ◽  
Andreev Reflection ◽  
Surface Condition ◽  
Three Dimensional ◽  
Point Contact ◽  
Scanning Tunneling Spectroscopy ◽  
Scanning Tunneling ◽  
Tunneling Microscopy ◽  
Zero Bias ◽  
Zero Bias Conductance

To study how Andreev reflection (AR) occurs between a superconductor and a three-dimensional topological insulator (TI), we use superconducting Nb tips to perform point-contact AR spectroscopy at 4.2 K on as-grown single crystals of Bi2Se3. Scanning tunneling spectroscopy and scanning tunneling microscopy are also used to characterize the superconducting tip and both the doping level and surface condition of the TI sample. The point-contact measurements show clear spectral signatures of AR, as well as a depression of zero-bias conductance with decreasing junction impedance. The latter observation can be attributed to interfacial Rashba spin-orbit coupling, and the presence of bulk bands at the Fermi level in our samples suggests that bulk states of Bi2Se3 are involved in the observed AR.

scholarly journals Quantum tunneling theory of Cooper pairs as bosonic particles

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Edgar J. Patiño ◽  
Daniel Lozano-Gómez
Keyword(s):  
Quantum Tunneling ◽  
Alternative Explanation ◽  
Tunnel Junctions ◽  
Tunneling Current ◽  
Phenomenological Theory ◽  
Low Energy ◽  
Cooper Pairs ◽  
Zero Bias ◽  
Conductance Peak ◽  
Zero Bias Conductance

AbstractWe propose a simple phenomenological theory for quantum tunneling of Cooper pairs, in superconductor/insulator/superconductor tunnel junctions, for a regime where the system can be modeled as bosonic particles. Indeed, provided there is an absence of quasiparticle excitations (fermions), our model reveals a rapid increase in tunneling current, around zero bias voltage, which rapidly saturates. This manifests as a zero bias conductance peak that strongly depends on the superconductors temperature in a non-monotonic way. This low energy tunneling of Cooper pairs could serve as an alternative explanation for a number of tunneling experiments where zero bias conductance peak has been observed.

Zero Bias Conductance Peak in HTS above Critical Temperature

2003 ◽  
Vol 17 (10n12) ◽  
pp. 505-518
Author(s):  
P. Mikheenko ◽  
R. Chakalov ◽  
R. I. Chakalova ◽  
M. S. Colclough ◽  
C. M. Muirhead
Keyword(s):  
Critical Temperature ◽  
Theoretical Prediction ◽  
Room Temperature ◽  
Andreev Reflection ◽  
Zero Bias ◽  
Conductance Peak ◽  
Extensive Search ◽  
Sample Heating ◽  
Ybco Sample ◽  
Zero Bias Conductance

It has recently been proposed that if phase incoherent preformed pairs exist above critical temperature (Tc), Andreev reflection should be observable above Tc too. A distinctive feature of Andreev reflection is a zero bias conductance peak (ZBCP) in the conductance/voltage (G/V) characteristics. We have performed an extensive search for the ZBCP in HTS/normal-metal planar junctions including samples which have been annealed in Argon in an attempt to induce underdoping and enhancement of the pseudogap temperature. We have observed a maximum in the G/V characteristics above Tc in a number of samples and contact configurations. In some samples this behavior persists up to room temperature, but has a very broad voltage scale, much greater than the gap voltage. In YBa 2 Cu 3 O x/ Au and YBa 2 Cu 3 O x/ Ag contacts the form and amplitude of the ZBCP is close to the theoretical prediction, but the origin of this effect could also be in sample heating. One particularly curious result comes from an Au/LSMO/YBCO sample that shows a clear sub-gap ZBCP over the temperature range 15–266 K.

Zero-bias conductance peak reduction by diffusive normal metal in high-Tc superconductor tunnel junctions

2005 ◽  
Vol 66 (8-9) ◽  
pp. 1401-1404
Author(s):  
Iduru Shigeta ◽  
Yukio Tanaka ◽  
Fusao Ichikawa ◽  
Yasuhiro Asano ◽  
Satoshi Kashiwaya
Keyword(s):  
Tunnel Junctions ◽  
Normal Metal ◽  
Peak Reduction ◽  
Zero Bias ◽  
High Tc ◽  
High Tc Superconductor ◽  
Conductance Peak ◽  
Zero Bias Conductance
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