High Field Superconductivity and Magnetic Moment Enhancement in Proximity Exchange Coupled GdN/NbN Nano-bridges*

Proximity effects in ferromagnetic insulator/superconductor (FI/SC) interface have been highly intriguing in terms of fundamental exploration as well as technological relevance [1,2]. We perform detailed investigations on GdN (FI) and NbN (SC) interface via magneto-transport properties of GdN/NbN-based nano-bridges and thin film heterostructures. We observe a clear enhancement of magnetic moment and a drastic increase of coercive field, below the superconducting transition temperature of NbN, which may be attributed to exchange coupled effect between GdN and NbN at the interface. Most interestingly, our nano-bridges exhibit a large magnetic field dependent superconductivity enhancement for fields > 5T similar to the Jaccarino effect [3]. The observed effect is temperature dependent implying a free energy dependence at the interface. Finally, we also discuss the exchange coupled interface effects and their implications in GdN/NbN system.

Ref.:
[1] J. S. Moodera, T. S. Santos and T. Nagahama, J. Phys.: Condens. Matter 19 165202 (2007);
[2] Y. Zhu et al., Nat. Mat. 16, 195 (2017);
[3] V. Jaccarino and M. Peter, Phys. Rev. Lett. 9, 290 (1962).