By María J. Martínez from Universidad de Zaragoza

Cuándo

Información de contacto

Nombre de contacto

Lucía Aballe

Correo electrónico

laballe@cells.es

Teléfono

93 592 4422

Página web

https://indico.cells.es/indico/event/210

Abstract

Performing magnetization studies on individual nanoparticles is a highly demanding task, especially when measurements need to be carried out under large sweeping magnetic fields or variable temperature. Yet, characterization under varying ambient conditions is paramount in order to fully understand the magnetic behavior of these objects, e.g., the formation of non-uniform states, the mechanisms leading to magnetization reversal, thermal stability or damping processes. This, in turn, is necessary for the integration of magnetic nanoparticles and nanowires into useful devices, e.g., spin-valves, racetrack memories or magnetic tip probes. Along the seminar I will show that YBa2Cu3O7 nano Superconducting QUantum Interference Devices (YBCO nanoSQUIDs) are particularly well suited for this task. I will show the successful characterization of a number of individual nanoparticles of soft magnetic materials with different shapes (nanodots, nanodiscs and nanowires). Magnetization measurements performed under sweeping magnetic fields (up to ~100 mT) and variable temperature (1.4 - 80 K) underscore the intrinsic differences between samples owing to their shape and the presence (or absence) of magnetocrystalline anisotropy. This yields different magnetization reversal mechanisms, e.g., nucleation/propagation of domain walls or nucleation/annihilation of magnetic vortices.

I will finish by presenting some preliminary theoretical studies on the possibility of strongly coupling photons living in a superconducting cavity and topological magnetic textures, e.g., magnetic vortices or skyrmions. Strong light−matter coupling means that cavity photons and other types of matter excitations are coherently exchanged. It is used to couple different qubits (matter) via a quantum bus (photons) or to communicate different types of excitations, e.g., transducing light into phonons or magnons. The strong coupling regime permits coherently exchanging a single photon and quanta of vortex gyration.