Prof. Jason Robinson
University of Cambridge

About the speaker

Jason Robinson is a Professor of Materials Physics at the University of Cambridge where he is the Head of the Department of Materials Science & Metallurgy, Director of the Quantum Materials & Devices Group, and co-director of the Centre for Materials Physics. His experimental research focuses on the development of quantum materials and devices for low power electronics, approaching key problems in the fields of spintronics, superconductivity, and quantum technologies. He has made major contributions to these fields, including the discovery of s-wave triplet Cooper pairs and pioneering the field of superconducting quantum spintronics.

Abstract: Supercurrents on a One-Way Path

Diodes are the one-way valves of electronics, allowing current to flow more easily in one direction than the other. A superconducting version of this idea, known as the superconducting diode effect, enables resistance-free supercurrents to favour one direction of flow along a wire or across a Josephson junction [1–3]. This effect is attracting strong interest because it could provide a route to ultra-low-energy superconducting electronics and offer new ways to probe unconventional superconducting states. The key challenge is to understand what causes this non-reciprocal behaviour and how it can be controlled. Intrinsic superconducting diode effects are expected when both inversion and time-reversal symmetries are broken, for example through structural asymmetry, spin–orbit coupling, and magnetic exchange fields, which can produce direction-dependent superconducting properties [1–3]. However, similar behaviour can also arise from device-level effects such as vortex motion, geometric asymmetry, magnetochiral responses, and screening currents [4–8]. In this talk, I will present our experimental work on superconducting diode effects in wires where vortex contributions can be ruled out, and where the results point instead towards screening currents and interfacial spin–orbit coupling as likely origins. By engineering the layer structure and thicknesses, we establish a controlled platform for superconducting diode behaviour and achieve diode efficiencies exceeding 70%. These results represent an important step towards low-energy superconducting spintronic and spin–orbitronic devices, in which supercurrents can flow without resistance while also acquiring a built-in sense of direction.

[1] M. Nadeem et al., Nat. Rev. Phys. 5, 558 (2023).
[2] F. Ando et al., Nature 584, 373 (2020).
[3] M. Amundsen, J. Linder, J. W. A. Robinson, I. Žutić, N. Banerjee, Rev. Mod. Phys. 96, 021003 (2024).
[4] A. Gutfreund et al., Nat. Commun. 14, 1630 (2023).
[5] Y. Hou et al., Phys. Rev. Lett. 131, 027001 (2023).
[6] B. Pal et al., Nat. Phys. 18, 1228 (2022).
[7] H. F. Legg et al., Phys. Rev. B 106, 104501 (2022).
[8] Davydova et al., Sci. Adv. 8, eabo0309 (2022).

Prof. Jason RobinsonUniversity of Cambridge

Prof. Jason Robinson
University of Cambridge