M. Motta
Federal University of São Carlos
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Publication
Featured researches published by M. Motta.
Applied Physics Letters | 2013
M. Motta; F Colauto; W.A. Ortiz; Joachim Fritzsche; J. Cuppens; W. Gillijns; Victor Moshchalkov; T. H. Johansen; Alvaro Sanchez; Alejandro Silhanek
A graded distribution of antidots in superconducting a-Mo79Ge21 thin films has been investigated by magnetization and magneto-optical imaging measurements. The pinning landscape has maximum density at the sample border, decreasing linearly towards the center. Its overall performance is noticeably superior than that for a sample with uniformly distributed antidots: For high temperatures and low fields, the critical current is enhanced, whereas the region of thermomagnetic instabilities in the field-temperature diagram is significantly suppressed. These findings confirm the relevance of graded landscapes on the enhancement of pinning efficiency, as recently predicted by Misko and Nori.
Scientific Reports | 2016
Jérémy Brisbois; M. Motta; Jonathan I. Avila; Gorky Shaw; Thibaut Devillers; Nora Dempsey; Savita K. P. Veerapandian; Pierre Colson; Benoı̂t Vanderheyden; Philippe Vanderbemden; W.A. Ortiz; Ngoc Duy Nguyen; Roman B. G. Kramer; Alejandro Silhanek
Local polarization of a magnetic layer, a well-known method for storing information, has found its place in numerous applications such as the popular magnetic drawing board toy or the widespread credit cards and computer hard drives. Here we experimentally show that a similar principle can be applied for imprinting the trajectory of quantum units of flux (vortices), travelling in a superconducting film (Nb), into a soft magnetic layer of permalloy (Py). In full analogy with the magnetic drawing board, vortices act as tiny magnetic scribers leaving a wake of polarized magnetic media in the Py board. The mutual interaction between superconducting vortices and ferromagnetic domains has been investigated by the magneto-optical imaging technique. For thick Py layers, the stripe magnetic domain pattern guides both the smooth magnetic flux penetration as well as the abrupt vortex avalanches in the Nb film. It is however in thin Py layers without stripe domains where superconducting vortices leave the clearest imprints of locally polarized magnetic moment along their paths. In all cases, we observe that the flux is delayed at the border of the magnetic layer. Our findings open the quest for optimizing magnetic recording of superconducting vortex trajectories.
IEEE Transactions on Applied Superconductivity | 2015
F Colauto; M. Motta; A. Palau; M. G. Blamire; T. H. Johansen; W.A. Ortiz
We have observed the occurrence of dendritic flux avalanches in an amorphous film of Mo84Si16. These events are understood to have a thermomagnetic origin and involve the abrupt penetration of bursts of magnetic flux taking place within a limited window of temperatures and magnetic fields. While dc-magnetometry allows one to determine the threshold fields for the occurrence of the thermomagnetic instabilities, magneto-optical imaging reveals the spatial distribution of magnetic flux throughout the sample. Conducting appropriate experiments, typical for this goal, avalanches were confirmed to be a characteristic of this material, ruling out the otherwise admissible possibility of an experimental artifact or a feature related to defects in the film. After the present observation, amorphous MoSi alloys, or a-MoSi, can be included in the gallery of superconducting materials exhibiting flux avalanches when in the form of thin films, a characteristic that must be carefully taken into consideration when one plans to employ films of those materials in applications.
New Journal of Physics | 2014
Jérémy Brisbois; Benoît Vanderheyden; F Colauto; M. Motta; W.A. Ortiz; Joachim Fritzsche; Ngoc Duy Nguyen; Benoît Hackens; Obaïd-Allah Adami; Alejandro Silhanek
Sudden avalanches of magnetic flux bursting into a superconducting sample undergo deflections of their trajectories when encountering a conductive layer deposited on top of the superconductor. Remarkably, in some cases the flux is totally excluded from the area covered by the conductive layer. We present a simple classical model that accounts for this behaviour and considers a magnetic monopole approaching a semi-infinite conductive plane. This model suggests that magnetic braking is an important mechanism responsible for avalanche deflection.
Review of Scientific Instruments | 2018
Gorky Shaw; Jérémy Brisbois; L.B.G.L. Pinheiro; J. Müller; S. Blanco Alvarez; Thibaut Devillers; Nora Dempsey; Jeroen E. Scheerder; J. Van de Vondel; Sorin Melinte; Philippe Vanderbemden; M. Motta; W.A. Ortiz; K. Hasselbach; Roman B. G. Kramer; Alejandro Silhanek
We present a detailed quantitative magneto-optical imaging study of several superconductor/ferromagnet hybrid structures, including Nb deposited on top of thermomagnetically patterned NdFeB and permalloy/niobium with erasable and tailored magnetic landscapes imprinted in the permalloy layer. The magneto-optical imaging data are complemented with and compared to scanning Hall probe microscopy measurements. Comprehensive protocols have been developed for calibrating, testing, and converting Faraday rotation data to magnetic field maps. Applied to the acquired data, they reveal the comparatively weaker magnetic response of the superconductor from the background of larger fields and field gradients generated by the magnetic layer.
Applied Physics Letters | 2013
Obaïd-Allah Adami; Dorin Cerbu; Damien Cabosart; M. Motta; J. Cuppens; W.A. Ortiz; Victor Moshchalkov; Benoît Hackens; Romain Delamare; J. Van de Vondel; Alejandro Silhanek
Physical Review B | 2016
Jérémy Brisbois; Obaïd-Allah Adami; J. I. Avila; M. Motta; W.A. Ortiz; Ngoc Duy Nguyen; Philippe Vanderbemden; Benoît Vanderheyden; R. B. G. Kramer; Alejandro Silhanek
Physical Review B | 2011
M. Motta; F Colauto; R. Zadorosny; T. H. Johansen; Rb Dinner; M. G. Blamire; G. W. Ataklti; Victor Moshchalkov; Alejandro Silhanek; W.A. Ortiz
Physical Review B | 2014
M. Motta; F Colauto; J. I. Vestgården; Joachim Fritzsche; Matias Timmermans; J. Cuppens; C. Attanasio; C. Cirillo; Victor Moshchalkov; J. Van de Vondel; T. H. Johansen; W.A. Ortiz; Alejandro Silhanek
Physica C-superconductivity and Its Applications | 2012
M. Motta; F Colauto; T. H. Johansen; Rb Dinner; M. G. Blamire; G. W. Ataklti; Victor Moshchalkov; Alejandro Silhanek; W.A. Ortiz