The review article “Imaging vortex cores and lattices with a scanning tunneling microscope”, among the 2014 highlights of SUST. See http://iopscience.iop.org/0953-2048/page/Highlights-of-2014
Instituto de ciencia de materiales “Nicolás Cabrera” colloquium program – Professor Paul C. Canfield (Ames Laboratory and Iowa State University)
As part of the master program Professor Canfield will give two lectures on design, growth and characterization of novel materials:
Tuesday 18th, 16:30, Seminar room módulo 03.
Wednesday 19th, 15:30, Seminar room módulo 03.
When: Tuesday, December 16th 2013. 11:30 am.
Speaker: Edgar J. Patiño
We report in-plane magnetization measurements on Ni/Nb/Ni/CoO and Co/Nb/Co/CoO spin valve structures with one of the ferromagnetic layers pinned by an antiferromagnetic layer. In samples with Ni below the superconducting transition Tc, our results show strong evidence of vortex flipping driven by ferromagnet magnetization. This is a direct consequence of the proximity effect that leads to vortex supercurrent leakage into the ferromagnets. Here, the polarized electron spins are subject to the vortices’ magnetic field, occasioning vortex flipping.
Such a novel mechanism has been made possible by fabrication of the ferromagnet/ superconductor/ferromagnet/antiferromagnet multilayered spin valves with an S layer thin enough to barely confine vortices inside as well as F layers thin enough to align and control magnetization within the plane.When Co is used, the vortex flipping effect is not observed. This is attributed to the shorter coherence length of Co. Interestingly, a reduction in the pinning field of about 400 Oe is observed instead when the Nb layer is in the superconducting state. This effect cannot be explained in terms of vortex fields. In view of these facts, any explanation must be directly related to the proximity effect and thus a remarkable phenomenon that deserves further investigation.
Ana Maldonado will defend her thesis on July 12th in the seminar room of the Condensed Matter Physics Department C3.
D.D. Osheroff will visit the Nicolás Cabrera Institute on Tuesday Feb 5. Seminar at 12h30. B. Cabrera will give a seminar Tuesday 12 at 12h30. More details here.