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©Nature publishing group. We thank Spanish MINECO grant FIS2013-45469 and CM grant S2013/MIT-2850 and EU COST Action MP-1201. D.G. acknowledges RYC-2012-09864., We present a simple nanodevice that can operate in two modes: i) non-volatile three-state memory and ii) reading device. The nanodevice can retain three well defined states −1, 0 and +1 and can operate in a second mode as a sensor for external magnetic fields. The nanodevice is fabricated with an array of ordered triangular-shaped nanomagnets embedded in a superconducting thin film gown on Si substrates. The device runs based on the combination of superconducting vortex ratchet effect (superconducting film) with the out of plane magnetization (nanomagnets). The input signals are ac currents and the output signal are dc voltages. The memory mode is realized without applying a magnetic field and the nanomagnet stray magnetic fields govern the effect. In the sensor mode an external magnetic field is applied. The main characteristic of this mode is that the output signal is null for a precise value of the external magnetic field that only depends on the fabrication characteristics of the nanodevice., Ministerio de Economía y Competitividad (MINECO), Comunidad de Madrid, EU COST Action, Depto. de Física de Materiales, Fac. de Ciencias Físicas, TRUE, pub

©2015 IOP Publishing Ltd and Deutsche Physikalische Gesellschaft. We thank Spanish MINECO grant FIS2013-45469 and CM grant S2013/MIT-2850 and EU COST Action MP-1201. D.G. acknowledges RYC-2012-09864., Smectic order has been generated in superconducting Nb films with two-fold symmetry arrays of symmetric pinning centers. Magnetic fields applied perpendicularly to the films develop a vortex matter smectic phase that is easily detected when the vortices are commensurate with the pinning center array. The smectic phase can be turned on and off with external parameters., Spanish MINECO, Comunidad de Madrid, EU COST Action, Depto. de Física de Materiales, Fac. de Ciencias Físicas, TRUE, pub

©2016 Optical Society of America. This work has been supported by the Ministerio Español de Economia y Competitividad (MINECO) MAT2013-48009-C4-1 and FIS2013-45469-C4-1 and Comunidad de Madrid (CM) S2013/MIT-2850. D. G. acknowledges RYC-2012-09864, MAD2D-CM Program (S2013/MIT- 007) and ESP2015-65597-C4-3-R for financial support., We have designed and fabricated a nanodevice exhibiting simultaneously ferromagnetic properties of nanostructures with plasmonic properties of continuous films. Our device consists of an array of nanomagnets on top of a continuous plasmonic film. The patterned nanomagnets magnetic state is single domain and well-defined shape anisotropy. Despite the presence of the patterned media on top of the Au film, the system exhibits surface plasmon resonance characteristics of a continuous film, i.e., propagating surface plasmon-polaritons., Ministerio Español de Economia y Competitividad (MINECO), Comunidad de Madrid, MAD2D-CM Program, BBVA foundation, Depto. de Física de Materiales, Fac. de Ciencias Físicas, TRUE, pub

©American Institute of Physics. We thank the support from the Spanish Ministerio de Economia y Competitividad Grant No. FIS2013-45469 and CAM Grant No. P2013/MIT-2850 and EU COST Action MP1201., In order to compare magnetic and non-magnetic pinning, we have nanostructured two superconducting films with the regular arrays of pinning centers: Cu (non-magnetic) dots in one case and Py (magnetic) dots in the other. For low applied magnetic fields, when all the vortices are pinned in the artificial inclusions, the magnetic dots prove to be better pinning centers, as has been generally accepted. Unexpectedly, when the magnetic field is increased and interstitial vortices appear, the results are very different: we show how the stray field generated by the magnetic dots can produce an effective reduction of the penetration length. This results in strong consequences in the transport properties, which, depending on the dot separation, can lead to an enhancement or worsening of the transport characteristics. Therefore, the election of the magnetic or non-magnetic character of the pinning sites for an effective reduction of dissipation will depend on the range of the applied magnetic field. Published by AIP Publishing., Ministerio de Economía y Competitividad (MINECO), Comunidad de Madrid, EU COST Action, Depto. de Física de Materiales, Fac. de Ciencias Físicas, TRUE, pub

En esta tesis se han estudiado varios efectos en el estado mixto de superconductores, cuando están en el régimen mesoscópico. Es decir, cuando el superconductor esta nanoestructurado con tamaños comparables a las longitudes físicas características del superconductor: la longitud coherente y la longitud de penetración. Se han utilizado dos tipos de superconductores y dos modos de introducir la nanoestructuración. Se han utilizado monocristales superconductores laminares, que están nanoestructurados en sí mismos; y películas delgadas superconductoras, en las que se han introducido artificialmente patrones de defectos no superconductores de los tamaños adecuados para poder tener efectos mesoscópicos. Para esto último se han crecido y nanoestructurado películas superconductoras mediante diversas técnicas de micro y nanofabricación (como pulverización catódica, litografía por haz de electrones, litografía óptica o ataque por iones reactivos) con el fin de generar potenciales artificiales de anclaje de vórtices. De esta manera se han estudiado diversos fenómenos de competencia entre superconductividad, magnetismo, geometría y longitudes características. Se ha estudiado la dinámica de vórtices mediante medidas de transporte eléctrico a bajas temperaturas y altos campos magnéticos. Para ello se ha usado un criostato de helio líquido de flujo continuo que permite variar la temperatura de la muestra entre 1.3 K y 300 K, con una bobina superconductora con capacidad de aplicar un campo magnético de 9T; un sistema de recuperación y licuefacción del helio; y un licuefactor de nitrógeno.., In this thesis, different effects have been studied in the mixed state of superconductors, when they are in a mesoscopic regime. That is, when the superconductor is nanostructured with typical sizes in the same scale that the characteristic lengths of the superconductor: the coherence and the penetration lengths. Two kind of superconductors, with two different ways to introduce nanostructuration have been used: layered superconducting monocrystals, which are nanostructured by their structure; and superconducting thin films, in which artificially generated non-superconducting defects have been embedded, with the proper size to generate mesoscopic effects. Fort the last, superconducting thin films have been grown, and have been nanostructured by means of different micro and nanofabrication techniques (such as magnetron sputtering, electron beam lithography or reactive ion etching), to generate artificial vortex pinning potentials. This way, different phenomena derived from the competition of superconductivity, magnetism, geometry and characteristic lengths have been studied. Vortex dynamics have been studied using electric transport measurements at low temperatures and high magnetic fields. For this purpose, a continuous flow liquid helium cryostat (which allows varying the temperature between 1.3 K and 300 K and has a superconducting solenoid capable of generate a 9T magnetic field), a helium recovery and liquefying system and a nitrogen liquefier have been used...

En esta tesis se han estudiado varios efectos en el estado mixto de superconductores, cuando están en el régimen mesoscópico. Es decir, cuando el superconductor esta nanoestructurado con tamaños comparables a las longitudes físicas características del superconductor: la longitud coherente y la longitud de penetración. Se han utilizado dos tipos de superconductores y dos modos de introducir la nanoestructuración. Se han utilizado monocristales superconductores laminares, que están nanoestructurados en sí mismos; y películas delgadas superconductoras, en las que se han introducido artificialmente patrones de defectos no superconductores de los tamaños adecuados para poder tener efectos mesoscópicos. Para esto último se han crecido y nanoestructurado películas superconductoras mediante diversas técnicas de micro y nanofabricación (como pulverización catódica, litografía por haz de electrones, litografía óptica o ataque por iones reactivos) con el fin de generar potenciales artificiales de anclaje de vórtices. De esta manera se han estudiado diversos fenómenos de competencia entre superconductividad, magnetismo, geometría y longitudes características. Se ha estudiado la dinámica de vórtices mediante medidas de transporte eléctrico a bajas temperaturas y altos campos magnéticos. Para ello se ha usado un criostato de helio líquido de flujo continuo que permite variar la temperatura de la muestra entre 1.3 K y 300 K, con una bobina superconductora con capacidad de aplicar un campo magnético de 9T; un sistema de recuperación y licuefacción del helio; y un licuefactor de nitrógeno..

© 2014 IOP Publishing Ltd. We thank the support from Spanish MINECO grants FIS2008-06249 (Grupo Consolidado), Consolider CSD2007-00010 and CAM grant S2009/MAT-1726. The magnetism aspects of this work were supported by the Office of Basic Energy Science, U.S. Department of Energy, under Grant No. DE FG03-87ER-45332 and Argentina UBACyT 661 and PICT 2008 No 753., Hybrid magnetic arrays embedded in superconducting films are ideal systems to study the competition between different physical (such as the coherence length) and structural length scales such as are available in artificially produced structures. This interplay leads to oscillation in many magnetically dependent superconducting properties such as the critical currents, resistivity and magnetization. These effects are generally analyzed using two distinct models based on vortex pinning or wire network. In this work, we show that for magnetic dot arrays, as opposed to antidot (i.e. holes) arrays, vortex pinning is the main mechanism for field induced oscillations in resistance R(H), critical current I-c(H), magnetization M(H) and ac-susceptibility chi(ac)(H) in a broad temperature range. Due to the coherence length divergence at T-c, a crossover to wire network behaviour is experimentally found. While pinning occurs in a wide temperature range up to T-c, wire network behaviour is only present in a very narrow temperature window close to T-c. In this temperature interval, contributions from both mechanisms are operational but can be experimentally distinguished., Ministerio de Economía y Competitividad (MINECO), Comunidad de Madrid, Depto. de Física de Materiales, Fac. de Ciencias Físicas, TRUE, pub

Hybrid magnetic arrays embedded in superconducting films are ideal systems to study the competition between different physical (such as the coherence length) and structural length scales such as are available in artificially produced structures. This interplay leads to oscillation in many magnetically dependent superconducting properties such as the critical currents, resistivity and magnetization. These effects are generally analyzed using two distinct models based on vortex pinning or wire network. In this work, we show that for magnetic dot arrays, as opposed to antidot (i.e. holes) arrays, vortex pinning is the main mechanism for field induced oscillations in resistance R(H), critical current Ic(H), magnetization M(H) and ac-susceptibility χ ac(H) in a broad temperature range. Due to the coherence length divergence at Tc, a crossover to wire network behaviour is experimentally found. While pinning occurs in a wide temperature range up to Tc, wire network behaviour is only present in a very narrow temperature window close to Tc. In this temperature interval, contributions from both mechanisms are operational but can be experimentally distinguished.