Periodic Magnetoconductance oscillation in hybrid Nb-2DEG-Nb ballistic Josephson junctions

The principle of quantum transport in Nb-In_0.75Ga_0.25As-Nb Josephson junctions is the phase coherent Andreev reflections at the interfaces of the Nb and 2DEG in In_0.75Ga_0.25As, where the microscopic phase of the quasiparticles wavefunction in In_0.75Ga_0.25As and the macroscopic phase of the superconducting order parameter, are combined [1]. The conductance in this system is influenced by several kinds of interference effects. For instance, the conductance oscillates in a step- or sinusoidal- manner when the hybrid junctions are placed in a magnetic field which gives rise to Aharonov-Bohm type effect observation even in such a simply connected system.
Here, we report the first experimental observation of periodic conductance oscillation in ballistic Nb-In_0.75Ga_0.25As 2DEG-Nb junctions in the low magnetic field. We demonstrate that the dI/dV (B) has a maximum close to zero field which drops in a step-like manner when the field is increased. When the field is reversely swept, a hysteresis is observed which is accompanied by oscillation of dI/dV in a sinusoidal manner with a periodicity of ~15 mT at and below T= 320 mK.
[1] K. Delfanazari, et al., Adv. Mater. 29, 1701836 (2017).