ABSTRACT
A diode is a one way switch for electrical charge currents. Recently, superconducting analogues have been demonstrated in which dissipationless supercurrents preferentially flow in one direction along a wire or across a Josephson junction, a phenomenon known as the superconducting diode effect (SDE) [1-3]. Such non reciprocal behaviour can originate when both inversion and time reversal symmetries are broken; for example through structural asymmetry and spin orbit coupling in the presence of a magnetic exchange field, induced via proximity to a magnetic material or by applying an external magnetic field. Microscopically, this can lead to finite momentum pairing and non reciprocal critical currents [1-3]. However, diode like responses can also originate from extrinsic mechanisms such as vortex dynamics [4] and geometric asymmetry [5] as well as magnetochiral effects [6,7], making it challenging to identify the underlying origin of the SDE in many experimental systems. From a fundamental and technological perspective, intrinsically generated superconducting diode effects are particularly attractive, as they provide a controlled route to non reciprocal spin-charge transport involving spin triplet correlations and spin polarisation. Disentangling intrinsic and extrinsic contributions is therefore a central challenge in the development of superconducting diodes. In this talk, I will present our recent experimental work on superconducting diodes in which extrinsic mechanisms are ruled out, enabling well-controlled spin triplet superconducting diode behaviour.
References [1] M. Nadeem, M. S. Fuhrer, and X. Wang, 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, and 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)
BIOGRAPHY
Jason Robinson has a Professorial Chair in 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.
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