PC-P-8
Magnetic field dependence of critical currents of cross-type Josephson junctions with inhomogeneous critical current density under oblique magnetic fields
16:45-18:15 29/11/2023
*Soma Haraoka1, Edmund Soji Otabe1, Yasunori Mawatari2
1. Kyushu Institute of Technology, Fukuoka, Japan
2. National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba, Japan
Magnetic field dependence of the DC critical currents in Josephson junctions shows Fraunhofer-type interference patterns. This magnetic interference is important for applications such as superconducting quantum interference devices. Miller et al. [1] reported that the cross-type junctions show no magnetic interference in perpendicular magnetic field. It has been reported that the DC critical currents of cross-type junctions with homogeneous critical current density in oblique magnetic fields exhibit anomalous magnetic interference [2].
In this study, we extend our earlier work [2] to consider the effect of the inhomogeneous critical current density Jc in cross-type junctions. We assume that the self-field and the magnetic screening current are sufficiently small. Figure 1 shows the dependence of the DC critical currents Ic on two-dimensional oblique magnetic fields, parallel Φx and perpendicular magnetic flux Φz . When Jc is homogeneous [Fig. 1(a)], magnetic interference disappears when the perpendicular field is large, |Φz| > |2 Φx| [2]. When Jc is large near the outer edges of the junction plane [Fig. 1(b)], on the other hand, magnetic interference appears even when the perpendicular field is large. In our presentation, we will also show about the magnetic interference of cross-type junctions with inhomogeneous Jc exposed to three-dimensional oblique magnetic fields.
Fig.1 Contour plots of the critical current Ic(Φx , Φz ) / Ic0 as the function of parallel Φx / Φ0 and perpendicular magnetic flux Φz / Φ0 in cross-type junctions (a) for homogeneous Jc and (b) for inhomogeneous Jc, where Φ0 is flux quantum and Ic0 = Ic(0,0) is the critical current at zero field.
[1] S. L. Miller, K. R. Biagi, J. R. Clem, and D. K. Finnemore, Phys. Rev. B 31, 2684 (1985).
[2] Y. Mawatari, J. Phys. D: Appl. Phys. 55, 200002 (2022)
[3] T. Ueda, E. S. Otabe, and Y. Mawatari, ISS2022, ED5-3, Nov. 29–Dec. 1, 2022, Nagoya, Japan.
This study is supported by JSPS Grant-in-Aid for Scientific Research 20K05314
