Control the Andreev bound states in the Al/InSbAs Josephson junctions

Chung-Ting Ke^1,2*, ChristianM. Moehle², PrasannaK. Rout², NayanA. Jainandunsing², DibyenduKuiri⁴, Di Xiao³, CandiceThomas³, MichaelJ. Manfra³, MichałP. Nowak⁴, Srijit Goswami²

¹Institute of Physics, Academia Sinica, Taiwan, Taiwan
²QuTechand KavliInstituteofNanoscience,, Delft Universityof Technology, Delft, Netherlands
³Departmentof Physicsand Astronomy, PurdueUniversity, West Lafayette,Indiana, USA
⁴AcademicCentrefor MaterialsandNanotechnology, AGHUniversityof Scienceand Technology, Krakow, Poland

* Presenter:Chung-Ting Ke, email:ctke@gate.sinica.edu.tw

In a superconductor/semiconductor/superconductor hybrid structure so-called Josephson junction (JJs), the charge transport is governed by the Andreev bound states (ABSs). These bound states that are formed by electron and hole counter propagations can be influenced by the normal region properties such as junction geometry, scattering mechanism, and spin-orbit effect. Hence, one can manipulate the ABS by changing the properties of the normal region. These ABSs provide a route to access the exotic quantum state such as Yu-Shiba-Rusinov states and Majorana bound states. In this talk, we present our effort in developing Josephson junction based on Al/InSbAs 2D electron gases (2DEGs) and the ability to control the phase of the ABSs through the gate and an external magnetic field.
Moreover, through the tunneling spectroscopy measurements, we perform ABS spectroscopy at the two ends of planar JJs and study the effects of the magnetic vector potential on the ABS spectrum. We show that the local superconducting phase difference arising from the vector potential is equal in magnitude and opposite in sign at the two ends, in agreement with a model that assumes localized ABSs near the tunnel barriers. Complemented with microscopic simulations, the results demonstrate that the local phase difference can be used to estimate the relative position of localized ABSs separated by a few hundred nanometers. Our results pave the way to manipulate exotic Andreev bound states through the magnetic vector potential for future applications.

Keywords: Josephson junction, hybrid material , Andreev bound states, superconductivity , 2D semiconductor