arXiv subjects

Ariel Brenac

Publications and source records attributed to Ariel Brenac.

6 recordsLinked to original sources

arXiv2021

Evidence of interfacial asymmetric spin scattering at ferromagnet-Pt interfaces

We measure the spin-charge interconversion by the spin Hall effect in ferromagnetic/Pt nanodevices. The extracted effective spin Hall angles (SHAs) of Pt evolve drastically with the ferromagnetic (FM) materials (CoFe, Co, and NiFe), when assuming transparent interfaces and a bulk origin of the spin injection/detection by the FM elements. By carefully measuring the interface resistance, we show that it is quite large and cannot be neglected. We then evidence that the spin injection/detection at the FM/Pt interfaces are dominated by the spin polarization of the interfaces. We show that interfacial asymmetric spin scattering becomes the driving mechanism of the spin injection in our samples.

cond-mat.mes-hall↗

arXiv2020

Independence of the inverse spin Hall effect with the magnetic phase in thin NiCu films

Large spin Hall angles have been observed in 3d ferromagnets, but their origin, and especially their link with the ferromagnetic order, remain unclear. Here, we investigate the inverse spin Hall effect of Ni60Cu40 and Ni50Cu50 across their Curie temperature using spin pumping experiments. We evidence that the inverse spin Hall effect in these samples is comparable to that of platinum, and that it is insensitive to the magnetic order. These results points towards a Heisenberg localized model of the transition, and suggest that the large spin Hall effects in 3d ferromagnets can be independent of the magnetic phase.

cond-mat.mtrl-sci↗

arXiv2020

Optomechanical mass spectrometry

It has been demonstrated in the recent years that nanomechanical mass spectrometry was well suited for the analysis of specific high mass species such as viruses. Still, the exclusive use of one-dimensional devices such as vibrating beams forces a trade-off between analysis time (related to capture area) and mass resolution (inversely proportional to device mass). Such devices also require complex readout schemes to simultaneously monitor multiple resonance modes, in particular when stiffness or shape come into play, which degrades mass resolution. These issues restrict nanomechanical MS to the analysis of species with specific properties. We report here the first demonstration of single-particle mass spectrometry with nano-optomechanical resonators fabricated with a Very Large Scale Integration process. The unique motion sensitivity of optomechanical techniques allows the use of resonators with new topologies. The device introduced here is designed to be impervious to particle position, stiffness or shape, opening the way to the analysis of large aspect ratio biological objects of great significance such as viruses with a tail or fibrils. Compared to top-down beam resonators with electrical read-out and state-of-the-art mass resolution, we show a three-fold improvement in capture area with no resolution degradation, despite the use of a single resonance mode. Short analysis time is in reach thanks to the sensitivity and bandwidth of optomechanical read-out and its compliance with telecom multiplexing techniques.

physics.app-ph↗

arXiv2017

Single-particle Mass Spectrometry with arrays of frequency-addressed nanomechanical resonators

One of the main challenges to overcome to perform nanomechanical Mass Spectrometry (NEMS-MS) analysis in a practical time frame stems from the size mismatch between the analyte beam and the extremely small nanomechanical detector area. We report here the demonstration of NEMS-MS with arrays of 20 individually addressed nanomechanical resonators where the number of inputs-outputs for the whole array is the same as that of a single resonator. While all resonators within an array are interconnected via two metal levels, each resonator is designed with a distinct resonance frequency which becomes its individual address. In order to perform single-particle Mass Spectrometry, the resonance frequencies of the two first modes of each NEMS within an array are monitored simultaneously. Using such an array, mass spectra of metallic aggregates in the MDa range are acquired with more than one order of magnitude improvement in analysis time due to the increase in capture cross section compared to individual resonators. A 20 NEMS array is probed in 150ms with the same mass limit of detection as a single resonator. Spectra acquired with a conventional Time- of-Flight (TOF) mass spectrometer in the same system show excellent agreement. As individual information for each resonator within the array is retained, the array becomes a particle imager, each resonator acting as a pixel. With this technique, we demonstrate how Mass Spectrometry Imaging (MSI) at the single particle level becomes possible by mapping a 4cm-particle beam in the MDa range and above.

physics.ins-det↗

arXiv2017

Electrical properties of single crystal Yttrium Iron Garnet ultra-thin films at high temperatures

We report a study on the electrical properties of 19 nm thick Yttrium Iron Garnet (YIG) films grown by liquid phase epitaxy. The electrical conductivity and Hall coefficient are measured in the high temperature range [300,400]~K using a Van der Pauw four-point probe technique. We find that the electrical resistivity decreases exponentially with increasing temperature following an activated behavior corresponding to a band-gap of $E_g\approx 2$ eV, indicating that epitaxial YIG ultra-thin films behave as large gap semiconductor, and not as electrical insulator. The resistivity drops to about $5\times 10^3$~$Ω\cdot \text{cm}$ at $T=400$ K. We also infer the Hall mobility, which is found to be positive ($p$-type) at 5 cm$^2$/(V$\cdot$sec) and about independent of temperature. We discuss the consequence for non-local transport experiments performed on YIG at room temperature. These electrical properties are responsible for an offset voltage (independent of the in-plane field direction) whose amplitude, odd in current, grows exponentially with current due to Joule heating. These electrical properties also induce a sensitivity to the perpendicular component of the magnetic field through the Hall effect. In our lateral device, a thermoelectric offset voltage is produced by a temperature gradient along the wire direction proportional to the perpendicular component of the magnetic field (Righi-Leduc effects).

cond-mat.mtrl-sci↗

arXiv2015

Neutral particle Mass Spectrometry with Nanomechanical Systems

Current approaches to Mass Spectrometry (MS) require ionization of the analytes of interest. For high-mass species, the resulting charge state distribution can be complex and difficult to interpret correctly. In this article, using a setup comprising both conventional time-of-flight MS (TOF-MS) and Nano-Electro-Mechanical-Systems-based MS (NEMS-MS) in situ, we show directly that NEMS-MS analysis is insensitive to charge state: the spectrum consists of a single peak whatever the species charge state, making it significantly clearer than existing MS analysis. In subsequent tests, all charged particles are electrostatically removed from the beam, and unlike TOF-MS, NEMS-MS can still measure masses. This demonstrates the possibility to measure mass spectra for neutral particles. Thus, it is possible to envisage MS-based studies of analytes that are incompatible with current ionization techniques and the way is now open for the development of cutting edge system architectures with unique analytical capability.

physics.ins-det↗