Observation of a.c. Josephson effect in gate tunable Josephson junction on topological insulator (Bi0.2Sb0.8)2 Te3 films

2019 ◽  
Author(s):  
Yuusuke Takeshige ◽  
Sadashige Matsuo ◽  
Russell Stewart Deacon ◽  
Kento Ueda ◽  
Yosuke Sato ◽  
...  
Keyword(s):  
Josephson Junction ◽  
Topological Insulator ◽  
Josephson Effect

scholarly journals Revealing the interference effect of Majorana fermions in a topological Josephson junction

2018 ◽  
Vol 9 ◽  
pp. 520-529 ◽  
Author(s):  
Jie Liu ◽  
Tiantian Yu ◽  
Juntao Song
Keyword(s):  
Josephson Junction ◽  
Interference Effect ◽  
Josephson Effect ◽  
Andreev Reflection ◽  
Local Density ◽  
Localized States ◽  
Majorana Fermions ◽  
Local Density Of States ◽  
Single Side ◽  
Period Oscillation

We study theoretically the local density of states (DOS) in a topological Josephson junction. We show that the well-known 4π Josephson effect originates from the interference effect between two Majorana fermions (MFs) that are localized at the Josephson junction. In addition, the DOS for electrons (holes) shows the 4π interference information along each parity conserved energy spectrum. The DOS displays a 2π period oscillation when two trivial states interfere with each other. This means that the DOS information may be used to distinguish the MFs from trivial localized states. We suggest that the interference effect and the DOS can be detected by using two STM leads or two normal leads. A single side lead can only detect the Andreev reflection tunneling process in the junction, which cannot reveal information about the interference effect in general. However, using two side leads, we can reveal information about the interference effect of the MFs as well as the DOS by combining Andreev reflection with the electron transmission process.

scholarly journals A Novel Treatment of the Josephson Effect

2021 ◽  
Author(s):  
Jacob Szeftel ◽  
Nicolas Sandeau ◽  
Michel Abou Ganthous
Keyword(s):  
Radio Frequency ◽  
Josephson Junction ◽  
Thermal Equilibrium ◽  
Josephson Effect ◽  
Negative Resistance ◽  
Persistent Currents ◽  
Novel Treatment ◽  
Rf Signal ◽  
Bound Electrons

A new picture of the Josephson effect is devised. The radio-frequency (RF) signal, observed in a Josephson junction, is shown to stem from bound electrons, tunneling periodically through the insulating film. This holds also for the microwave mediated tunneling. The Josephson effect is found to be conditioned by the same prerequisite worked out previously for persistent currents, thermal equilibrium and occurence of superconductivity. The observed negative resistance behaviour is shown to originate from the interplay between the normal and superconducting currents.

scholarly journals Unconventional Josephson Effect in Hybrid Superconductor-Topological Insulator Devices

2012 ◽  
Vol 109 (5) ◽  
Author(s):  
J. R. Williams ◽  
A. J. Bestwick ◽  
P. Gallagher ◽  
Seung Sae Hong ◽  
Y. Cui ◽  
...  
Keyword(s):  
Topological Insulator ◽  
Josephson Effect

scholarly journals Josephson effect in normal and ferromagnetic topological-insulator junctions: Planar, step, and edge geometries

2014 ◽  
Vol 90 (4) ◽  
Author(s):  
Jennifer Nussbaum ◽  
Thomas L. Schmidt ◽  
Christoph Bruder ◽  
Rakesh P. Tiwari
Keyword(s):  
Topological Insulator ◽  
Josephson Effect

scholarly journals Gate controlled anomalous phase shift in Al/InAs Josephson junctions

2020 ◽  
Vol 11 (1) ◽  
Author(s):  
William Mayer ◽  
Matthieu C. Dartiailh ◽  
Joseph Yuan ◽  
Kaushini S. Wickramasinghe ◽  
Enrico Rossi ◽  
...  
Keyword(s):  
Phase Shift ◽  
Josephson Junction ◽  
Phase Difference ◽  
Josephson Junctions ◽  
Quantum Interference ◽  
Josephson Effect ◽  
Orbit Coupling ◽  
Spin Orbit Coupling ◽  
Spin Orbit ◽  
Superconducting Quantum Interference Device

AbstractIn a standard Josephson junction the current is zero when the phase difference between superconducting leads is zero. This condition is protected by parity and time-reversal symmetries. However, the combined presence of spin–orbit coupling and magnetic field breaks these symmetries and can lead to a finite supercurrent even when the phase difference is zero. This is the so called anomalous Josephson effect—the hallmark effect of superconducting spintronics—which can be characterized by the corresponding anomalous phase shift. Here we report the observation of a tunable anomalous Josephson effect in InAs/Al Josephson junctions measured via a superconducting quantum interference device. By gate controlling the density of InAs, we are able to tune the spin–orbit coupling in the Josephson junction. This gives us the ability to tune the anomalous phase, and opens new opportunities for superconducting spintronics, and new possibilities for realizing and characterizing topological superconductivity.

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