[12a-S302-8~11] 10.4 Semiconductor spintronics, superconductor, multiferroics

[12a-S302-8] Giant enhancement of Josephson critical currents in CoFeB through thermal annealing

〇SACHIO KOMORI^1,2, Juliet Thompson², Jason Robinson² (1.Nagoya Univ., 2.Cambridge Univ.)

Keywords:spintronics, superconductivity, Josephson junctions

The electrical and structural properties of Co₄₀Fe₄₀B₂₀ (CoFeB) alloy are tunable with thermal annealing. This is key in the optimization of CoFeB-based spintronic devices, where the advantageously low magnetic coercivity, high spin polarization, and controllable magnetocrystalline anisotropy are utilised. So far, there has been no report on superconducting devices based on CoFeB. Here, we present our recent experiments on Nb/CoFeB/Nb Josephson devices and demonstrate an enhancement of the critical current by up to 700% following thermal annealing due to increased structural ordering of the CoFeB. Thermal annealing optimization of Josephson coupling across CoFeB demonstrated in this work is an absolutely new concept in the field of superconducting spintronics and hence the results are the key towards the development of superconducting spintronic devices in which tunable attractive properties of CoFeB are utilized.