J.M. Ruiz

• Escola Universitària Salesiana de Sarrià

Carbon-based electrode materials have widely been used in supercapacitors. Unfortunately, the fabrication of the supercapacitors includes a polymeric binding material that leads to an undesirable addition of weight along with an increased charge transfer resistance. Herein, binder-free and lightweight electrodes were fabricated using powder process...

Activated carbons (ACs) have been used as electrode material in commercial electric double-layer capacitors (EDLC) due to their low cost, high specific surface area, and chemical stability. Unfortunately, the supercapacitive performance of AC is not satisfactory due to their low conductivity.On the other hand, carbon nanofibers (CNFs) based EDLC ex...

In this paper the power consumption and power integrity of a CMOS ring oscillator has been analysed when their pFETs are subjected to negative bias temperature instability (NBTI). The impact of pFET under NBTI has been experimentally quantified whereas CMOS ring oscillator power consumption and power integrity have been evaluated by means of electr...

In this paper the switching noise of a CMOS ring oscillator has been analysed when their pFETs are subjected to negative bias temperature instability (NBTI). The impact of pFET under NBTI has been experimentally quantified whereas CMOS ring oscillator frequency and the switching noise has been analysed by means of electrical full-model simulation....

The continuous scaling of CMOS circuits has set the MOSFET transistor in the nanoelectronic era. In this context, the functionality and complexity of integrated circuits (ICs) are growing up. However, the operation voltage has been continuously reduced. The higher complexity of ICs has allowed including electronic systems in a lot of safety critica...

Magnetization and resistivity measurements, embracing a temperature range 2-300 K, have been performed in glass-coated Co6sMnTSiloBls amorphous microwires. The relation between both types of measurements is analysed. Similar trends of the temperature dependence of the domain structure, magnetization and resistivity are observed. An increase of resi...

Magnetic relaxation investigations of Cu/Fe4 Sm/Cu multilayers from 20 K to 1.6 K at low and high fields have been performed. The constancy of both the magnetic viscosity and the coercive field below 2.5 K suggests that this temperature corresponds to the crossover between thermal and quantum regimes.

Amorphous thin films of Fe/Sm, prepared by evaporation methods, have been magnetically characterized and the results were interpreted in terms of the random magnets theory. The samples behave as 2D and 3D random magnets depending on the total thickness of the film. From our data the existence of orientational order, which greatly influences the mag...

The low-temperature isothermal magnetization curves, M(H), of ${\mathrm{SmCo}}_{4}$ and ${\mathrm{Fe}}_{3}$Tb thin films are studied according to the two-dimensional correlated spin-glass model of Chudnovsky. We have calculated the magnetization law in approach to saturation and shown that the M(H) data fit well the theory at high and low fields. I...

In this paper we report on the magnetic behaviour of Fe/Y amorphous multilayers with different layer thicknesses as a function of the applied field and temperature. The isothermal magnetization data M(H) clearly show the features predicted in the theory of 2D and 3D random magnets depending on the magnetic layer thickness.

This chapter presents the observation of quantum tunnelling of the magnetization vector in small particles with and without domain walls. The chapter describes an experiment and discusses the results obtained on the magnetic viscosity in Fe/Cu, Dy/Cu, Fe/Sm, and SmCo multilayers in low fields and temperatures above 1.7 K. All the systems were magne...

The observation of the quantum tunneling of magnetization has been accomplished in different multilayer systems of transition and rare earth metals. We have measured the time dependence of the thermoremanence magnetization up to temperaturesof 1.7 K. The tendency of the magnetic viscosity to have finite intercept at T = 0 and/or the plateau in the...

In this paper we report on the first observation of both the quantum nucleation of a ferromagnet and the space-time instantons in condensed matter physics. Our conclusions are based on the observance of non-thermally activated time dependent phenomena at temperatures below 3 K in the 2D random magnet SmCo multilayer.

Fe/RE (rare earth) compositionally modulated structures made up of alternating layers of Fe and RE atoms by using electron beam evaporation have been studied. We have used RE magnetic (Dy, Tb) and nonmagnetic (Y, La) atoms to investigate how different RE atoms may affect the magnetic properties of the whole modulated structure. In the low field reg...