Examinando por Autor "Menghini, M."

Mostrando 1 - 3 de 3

Acceso Abierto
Little–Parks effect governed by magnetic nanostructures with out-of-plane magnetization
(Springer Nature Research Journals, 2020-06-25) De Ory, M. C.; Rollano, V.; Gómez, A.; Menghini, M.; Muñoz Noval, A.; González, E. M.; Vicent, J. L.; Agencia Estatal de Investigación (AEI); Comunidad de Madrid; Muñoz Nova, A. [0000-0003-3236-5509]; González, E. M. [0000-0001-9360-3596]; Gómez, A. [0000-0002-8752-1401]; Unidad de Excelencia Científica María de Maeztu Centro de Astrobiología del Instituto Nacional de Técnica Aeroespacial y CSIC, MDM-2017-0737; Centros de Excelencia Severo Ochoa, INSTITUTO MADRILEÑO DE ESTUDIOS AVANZADOS EN NANOCIENCIA, SEV-2016-0686
Little–Parks effect names the oscillations in the superconducting critical temperature as a function of the magnetic field. This effect is related to the geometry of the sample. In this work, we show that this effect can be enhanced and manipulated by the inclusion of magnetic nanostructures with perpendicular magnetization. These magnetic nanodots generate stray fields with enough strength to produce superconducting vortex–antivortex pairs. So that, the L–P effect deviation from the usual geometrical constrictions is due to the interplay between local magnetic stray fields and superconducting vortices. Moreover, we compare our results with a low-stray field sample (i.e. with the dots in magnetic vortex state) showing how the enhancement of the L–P effect can be explained by an increment of the effective size of the nanodots.
Acceso Abierto
Realization of macroscopic ratchet effect based on nonperiodic and uneven potentials
(Nature Research Journals, 2021-08-16) Rollano, V.; Gómez, A.; Muñoz Noval, A.; Velez, M.; De Ory, M. C.; Menghini, M.; González, E. M.; Vicent, J. L.; Agencia Estatal de Investigación (AEI); Comunidad de Madrid; Centros de Excelencia Severo Ochoa, INSTITUTO MADRILEÑO DE ESTUDIOS AVANZADOS EN NANOCIENCIA, SEV-2016-0686
Ratchet devices allow turning an ac input signal into a dc output signal. A ratchet device is set by moving particles driven by zero averages forces on asymmetric potentials. Hybrid nanostructures combining artificially fabricated spin ice nanomagnet arrays with superconducting films have been identified as a good choice to develop ratchet nanodevices. In the current device, the asymmetric potentials are provided by charged Néel walls located in the vertices of spin ice magnetic honeycomb array, whereas the role of moving particles is played by superconducting vortices. We have experimentally obtained ratchet effect for different spin ice I configurations and for vortex lattice moving parallel or perpendicular to magnetic easy axes. Remarkably, the ratchet magnitudes are similar in all the experimental runs; i. e. different spin ice I configurations and in both relevant directions of the vortex lattice motion. We have simulated the interplay between vortex motion directions and a single asymmetric potential. It turns out vortices interact with uneven asymmetric potentials, since they move with trajectories crossing charged Néel walls with different orientations. Moreover, we have found out the asymmetric pair potentials which generate the local ratchet effect. In this rocking ratchet the particles (vortices) on the move are interacting each other (vortex lattice); therefore, the ratchet local effect turns into a global macroscopic effect. In summary, this ratchet device benefits from interacting particles moving in robust and topological protected type I spin ice landscapes.
Acceso Abierto
Vortex dynamics controlled by local superconducting enhancement
(IOP Science Publishing, 2019-11-29) Rollano, V.; Gómez, A.; Muñoz Noval, A.; Del Valle, J.; Menghini, M.; De Ory, M. C.; Prieto, J. L.; Navarro, E.; González, E. M.; Vicent, J. L.; Agencia Estatal de Investigación (AEI); Comunidad de Madrid; Menghini, M. [0000-0002-1744-798X]; Navarro, E. [0000-0002-2807-3805]; Mñoz Noval, Á. [0000-0003-3236-5509]; Prieto, J. L. [0000-0003-2298-2714]; González, E. M. [0000-0001-9360-3596]; Gómez, A. [0000-0002-8752-1401]; Del Valle Granada, J. [0000-0002-6210-5321]; Centros de Excelencia Severo Ochoa, INSTITUTO MADRILEÑO DE ESTUDIOS AVANZADOS EN NANOCIENCIA, SEV-2016-0686; Unidad de Excelencia Científica María de Maeztu Centro de Astrobiología del Instituto Nacional de Técnica Aeroespacial y CSIC, MDM-2017-0737
A controlled local enhancement of superconductivity yields unexpected modifications in the vortex dynamics. This local enhancement has been achieved by designing an array of superconducting Nb nanostructures embedded in a V superconducting film. The most remarkable findings are: (i) vanishing of the main commensurability effect between the vortex lattice and the array unit cell, (ii) hysteretic behavior in the vortex dynamics, (iii) broadening of the vortex liquid phase and (iv) strong softening of the vortex lattice. These effects can be controlled and they can be quenched by reducing the Nb array superconducting performance applying an in-plane magnetic field. These results can be explained by taking into account the repulsive potential landscape created by the superconducting Nb nanostructures on which vortices move.