Contact: International Center for Materials Nanoarchitectonics Nanoarchitectonics (MANA (MANA), Nakata (ex. 8806) ), Nakata (ex. 8806) Venue: Seminar Room #431, MANA Bldg., Namiki Date: Time: Title: Vortex Transitions in Hybrid Mesoscopic Superconductors Dr. Goran Karapetrov Materials Science Division, Argonne National Laboratory Superconductors containing mesoscopic defects have superior magnetic properties due to confinement of Abrikosov vortices by the pinning potential landscape. Confinement of vortices can be introduced by artificially-engineered structures with mesoscopic dimensions that correspond to the coherence length of the superconductor. We will use scanning tunnelling microscopy and spectroscopy as well as transport measurements to focus on hybrid superconducting systems containing periodic normal metal and ferromagnetic structures. In the case of S-N hybrids we observe co-existence of strongly interacting multiquanta vortex lattice and interstitial Abrikosov vortices that form a composite magnetic flux distribution which undergoes a series of transitions between different topological configuration states. Scanning tunnelling spectroscopy images show the evolution of vortex topological states when the number of flux quanta in the system changes. On the other hand, in S-F hybrids we focus on magneto-transport properties and STM in magnetically coupled superconductor-ferromagnet bilayers. The rotatable anisotropy Permalloy ferromagnet with stripe domain structure induces in-plane anisotropy in superconducting order parameter. Superconducting phase diagram shows that near the superconductor-normal state phase boundary the superconductivity is localized in narrow mesoscopic channels just above the magnetic domain walls. By changing the in-plane direction of magnetic stripe domains it is possible to re-configure the direction of the superconducting channels and controllably rotate the direction of the in-plane transport anisotropy axis in the superconductor. The bilayer also exhibits pronounced commensurability features that are related to the matching periodicities of the Abrikosov vortex lattice and the magnetic stripe domains. Intricate vortex configurations and geometrical transitions are explored using low- temperature STM in conjunction with Ginzburg Landau simulation. 16:00-17:00 16:00-17:00 Dec 1 st Monday Dec 1 st Monday
Venue: Seminar Room #431, MANA Bldg., Namiki Monday 16:00 … · 2012. 1. 19. · Superconductors containing mesoscopic defects have superior magnetic properties due to confinement
Contact: International Center for Materials
NanoarchitectonicsNanoarchitectonics (MANA(MANA), Nakata (ex.
8806)), Nakata (ex. 8806)
Venue: Seminar Room #431, MANA Bldg., NamikiDate: Time:
Title: Vortex Transitions in Hybrid
MesoscopicSuperconductors
Dr. Goran KarapetrovMaterials Science Division, Argonne National
Laboratory
Superconductors containing mesoscopic defects have superior
magnetic properties due to confinement of Abrikosov vortices by the
pinning potential landscape. Confinement of vortices can be
introduced by artificially-engineered structures with mesoscopic
dimensions that correspond to the coherence length of the
superconductor. We will use scanning tunnelling microscopy and
spectroscopy as well as transport measurements to focus on hybrid
superconducting systems containing periodic normal metal and
ferromagnetic structures.In the case of S-N hybrids we observe
co-existence of strongly interacting multiquanta vortex lattice and
interstitial Abrikosov vortices that form a composite magnetic flux
distribution which undergoes a series of transitions between
different topological configuration states. Scanning tunnelling
spectroscopy images show the evolution of vortex topological states
when the number of flux quanta in the system changes.On the other
hand, in S-F hybrids we focus on magneto-transport properties and
STM in magnetically coupled superconductor-ferromagnetbilayers. The
rotatable anisotropy Permalloy ferromagnet with stripe domain
structure induces in-plane anisotropy in superconducting order
parameter. Superconducting phase diagram shows that near the
superconductor-normal state phase boundary the superconductivity is
localized in narrow mesoscopic channels just above the magnetic
domain walls. By changing the in-plane direction of magnetic stripe
domains it is possible to re-configure the direction of the
superconducting channels and controllably rotate the direction of
the in-plane transport anisotropy axis in the superconductor. The
bilayer also exhibits pronounced commensurability features that are
related to the matching periodicities of the Abrikosov vortex
lattice and the magnetic stripe domains. Intricate vortex
configurations and geometrical transitions are explored using
low-temperature STM in conjunction with Ginzburg Landau
simulation.
![arxiv.orgarXiv:cond-mat/9905258v1 [cond-mat.supr-con] 18 May 1999 Diss. ETH No. 13068 Transport and Magnetism in Mesoscopic Superconductors A dissertation submitted to the SWISS FEDERAL](https://img.pdfslide.us/doc/110x75/60bcab655fb8d562c844d03f/arxivorg-arxivcond-mat9905258v1-cond-matsupr-con-18-may-1999-diss-eth-no.jpg)
