Spin-based electronics (spintronics) which uses the electron spin for reading, writing and processing information plays a crucial role in modern computing and data storage technologies. However, spintronic devices still rely on dissipative charge currents as the source of spin currents and suffer from large heat dissipation. This problem could be potentially addressed using superconductors.
However, conventional superconductivity does not carry a net spin since it is formed of electron pairs with anti-parallel spins – the singlet Cooper pair. In the last decade several experiments [1,2] confirmed the existence of an exotic spin-triplet superconductivity in superconductor-ferromagnet (S/F) thin film hybrids which is formed of equal spin-paired electrons (triplet Cooper pairs) and carries a net spin. However, generating this triplet superconductivity usually requires S/F hybrid structures with complex magnetic textures .
Recently, we demonstrated that S/F hybrids with interfacial spin-orbit coupling and without complex magnetic textures can be used to generate triplets . In addition to strikingly simplifying the thin film structures, presence of spin-orbit coupling in S/F structures raises intriguing new possibilities such as magnetisation reorientation purely driven by superconductivity or magnetically tunable superconducting transistors.
This PhD project will address two poorly understood but critical issues in establishing this new and exciting direction: the exact microscopic mechanisms of the interplay of the magnetism and the spin-orbit field leading to the generation of triplets and the role of thin film interfaces in determining the efficiency of triplet generation. The student will use sputtering to grow the thin film heterostructures and use state-of-the-art x-ray and electron and atomic force microscopy techniques to characterize the interfaces. The student will also develop expertise the fabrication and low temperature magnetic and electrical characterisation of devices.
Through this project, the student will be able to contribute to the rapidly developing field of superconducting spintronics and also be part of our ongoing collaborations with University of Cambridge and the Advanced Light Source, Berkeley. This project is ideal for students with a strong interest in experimental condensed matter physics and materials science.
This is a self-funded project only.
2:1 and above
Start date: January 2021
Full-time (3 years), Part-time (6 years)
Fee band: UK/EU: TBC; international: £22,350
1. J. Linder and J. W. A. Robinson Nature Physics, 11, 307 (2015).
2. N. Banerjee, et al., Physics World, 32, 4, (2019)
3. N. Banerjee, et al., Nature Communications, 5:4771 (2014).
4. N. Banerjee, et al., Phys. Rev. B, 97, 184521 (2018).