Vortex dynamics at the sub-nanometer scale - Yonathan Anahory

Recorded from IQC's NanoMRI conference 2015. Nanoscale superconducting quantum interference devices (SQUID) residing on the apex of a quartz tip small outline transistor (SOT), suitable for scanning probe microscopy with record size, spin sensitivity, and operating magnetic fields, are presented[1]. We have developed SOT made of lead (Pb) with an effective diameter of 46 nm and flux noise of Φn = 50 nΦ0/Hz1/2 at 4.2 K that is operational up to unprecedented high fields of 1 T[2]. The corresponding spin sensitivity of the device is Sn = 0.38 μB/Hz1/2, which is about two orders of magnitude more sensitive than any other SQUID to date. We use this technique to study vortex matter in superconductors. At low vortex density and low currents, we measure the fundamental dependence of the elementary pinning force of multiple defects on the vortex displacement. The outstanding magnetic sensitivity of the SOT allows probing vortex displacements as small as 10 pm[3]. This study reveals rich internal structure of the pinning potential and unexpected phenomena such as softening of the restoring force and abrupt depinning. The results shed new light on the importance of multi-scale random disorder on vortex dynamics and thermal relaxation. [1] A. Finkler, Y. Segev, Y. Myasoedov, M. L. Rappaport, L. Neeman, D. Vasyukov, E. Zeldov, M. E. Huber, J. Martin and A. Yacoby, Nano Lett. 10, 1046 (2010) [2] D. Vasyukov, Y. Anahory, L. Embon, D. Halbertal, J. Cuppens, L. Neeman, A. Finkler, Y. Segev, Y. Myasoedov, M. L. Rappaport, M. E. Huber, and E. Zeldov, Nature Nanotech. 8, 639 (2013). [3] L. Embon, Y.Anahory, A. Suhov, D. Halbertal, J. Cuppens, A. Yakovenko, A. Uri, Y. Myasoedov, M.L. Rapparport, M.E. Huber, A. Gurevich and E. Zeldov, Scientific Reports 5 (2015) 7598