Spin-polarised supercurrents: From fundamentals to functional devices

There are almost no materials where ferromagnetism and superconductivity can coexist. Their fundamental antagonism arises from the nature of electron pairing in these materials - parallel for ferromagnetism and antiparallel (singlet) for superconductivity. However, recent theoretical and experimental evidences [1] suggest an unique form of odd-frequency equal-spin (triplet) superconductivity that arises at carefully engineered interfaces between ferromagnets and superconductors. These equal-spin Cooper pairs are immune to the pair breaking exchange field in a ferromagnet and can propagate over length scales which are significantly longer than the singlet pair coherence lengths. These dissipationless triplet currents carry a net spin which raises the intriguing possibility of ultra low-dissipation spintronics.
In this talk, following a brief introduction I will focus on the control of spin-polarised supercurrents in nanoscale devices [2] and spin selectivity of triplet Cooper pairs [3] showing its importance in relation to the development of ultra low-dissipation spintronics. I will also discuss strategies to develop functional devices based on triplet supercurrents and possible ways to exploit spin-orbit
interaction as a source of odd-frequency triplet superconductivity.

1. J. Linder and J. W. A. Robinson, Nature Physics 11, 307–315 (2015).
2. N. Banerjee et al., Nature Communications 5:4771 (2014).
3. N. Banerjee et al., Nature Communications 5:3048 (2014).

Speaker biography
Niladri is currently a postdoc in the Materials Science Department at University of Cambridge and a Research Fellow at Wolfson College, Cambridge. He obtained his PhD from St John’s College, University of Cambridge in 2011 working in the Device Materials Group under Prof. Mark Blamire.
He was the first recipient of the Dr Manmohan Singh Scholarship for PhD studies and also received the Overseas Research Student Award. Niladri obtained his M.Tech in Materials Engineering from IIT Kanpur and B.E. in Metallurgical and Materials Engineering from Bengal Engineering and Science University, Shibpur (now IIEST, Shibpur).