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Electronic properties of individual diarylethene molecules studied using scanning tunneling spectroscopy

REA Auditado

The investigation of the electronic conduction through monosulfurdiarylethene (1S-DE) immobilized in an insulating dodecanethiol matrix on a gold surface was addressed. Scanning tunneling spectroscopy allows to probe spatially the frontier molecular orbitals of 1S-DE at 77K. We locally extracted the electronic highest occupied molecular orbital-lowest unoccupied molecular orbital gap of 1S-DE with the value of 1.56 eV.

Tema: general: 

• Ingeniería y Ciencias Aplicadas›Ingeniería›Ingeniería Civil y Ciencia de los Materiales

Spin caloritronics

REA Auditado

Spintronics is about the coupled electron spin and charge transport in condensed-matter structures and devices. The recently invigorated field of spin caloritronics focuses on the interaction of spins with heat currents, motivated by newly discovered physical effects and strategies to improve existing thermoelectric devices. Here we give an overview of our understanding and the experimental state-of-the-art concerning the coupling of spin, charge and heat currents in magnetic thin films and nanostructures.

Tema: general: 

• Ingeniería y Ciencias Aplicadas›Ingeniería›Ingeniería Civil y Ciencia de los Materiales

Nanoscale temperature sensing using the Seebeck effect

REA Auditado

We experimentally study the effect of Joule heating on the electron temperature in metallic nanoscale devices and compare the results with a diffusive 3D finite element model. The temperature is probed using four thermocouples located at different distances from the heater. A good quantitative agreement, within 30%, between the experimental data and the modeling is obtained. Since we observe a strong thickness dependence of the electrical conductivity of our metals, we find that the Joule heating in nanoscale devices is often incorrectly calculated if bulk conductivities are used.

Tema: general: 

• Ingeniería y Ciencias Aplicadas›Ingeniería›Ingeniería Civil y Ciencia de los Materiales

Thermoelectric Detection of Ferromagnetic Resonance of a Nanoscale Ferromagnet

REA Auditado

We present thermoelectric measurements of the heat dissipated due to ferromagnetic resonance of a Permalloy strip. A microwave magnetic field, produced by an on-chip coplanar strip waveguide, is used to drive the magnetization precession. The generated heat is detected via Seebeck measurements on a thermocouple connected to the ferromagnet. The observed resonance peak shape is in agreement with the Landau-Lifshitz-Gilbert equation and is compared with thermoelectric finite-element modeling.

Tema: general: 

• Ingeniería y Ciencias Aplicadas›Ingeniería›Ingeniería Civil y Ciencia de los Materiales

Ion energy distribution measurements in rf and pulsed dc plasma discharges

REA Auditado

A commercial retarding field analyzer is used to measure the time-averaged ion energy distributions of impacting ions at the powered electrode in a 13.56MHz driven, capacitively coupled, parallel plate discharge operated at low pressure. The study is carried out in argon discharges at 10mTorr where the sheaths are assumed to be collisionless. The analyzer is mounted flush with the powered electrode surface where the impacting ion and electron energy distributions are measured for a range of discharge powers.

Tema: general: 

• Ingeniería y Ciencias Aplicadas›Ingeniería›Ingeniería Civil y Ciencia de los Materiales

Relation between microstructure and adhesion of hot dip galvanized zinc coatings on dual phase steel

REA Auditado

The microstructure of hot dip galvanized zinc coatings on dual phase steel was investigated by electron microscopy and the coating adhesion characterized by tensile testing. The zinc coating consists of a zinc layer and columnar ζ-FeZn13 particles on top of a thin inhibition layer adjacent to the steel substrate. The inhibition layer is a thin compact and continuous layer that consists of η-Fe2Al5–xZnx fine and coarse particles. The coarse faceted particles are on top and fine faceted particles are at the bottom.

Tema: general: 

• Ingeniería y Ciencias Aplicadas›Ingeniería›Ingeniería Civil y Ciencia de los Materiales

Formation of inversion layers in organic field-effect transistors

REA Auditado

An inversion current in unipolar organic field-effect transistors is not observed, which can be due to trapping of electrons or to negligible electron injection. Here, we distinguish between both cases by studying the depletion current of unipolar p-type transistors based on a deliberately doped organic semiconductor. For each doping level, the current can be completely pinched off, which unambiguously shows that no inversion layer is formed.

Tema: general: 

• Ingeniería y Ciencias Aplicadas›Ingeniería›Ingeniería Civil y Ciencia de los Materiales

Roughness correction to the Casimir force at short separations: Contact distance and extreme value statistics

REA Auditado

So far there has been no reliable method to calculate the Casimir force at separations comparable to the root-mean square of the height fluctuations of the surfaces. Statistical analysis of rough gold samples has revealed the presence of peaks considerably higher than the root-mean-square roughness. These peaks redefine the minimum separation distance between the bodies and can be described by extreme value statistics.

Tema: general: 

• Ingeniería y Ciencias Aplicadas›Ingeniería›Ingeniería Civil y Ciencia de los Materiales

Self-healing performance of Ti2AlC ceramic

REA Auditado

This work concentrates on revealing the oxidation-induced healing performance of Ti2AlC. The microstructures of three kinds of defects: notches on single crystal, surface cavity and crack, after healing by oxidation in air at 1200 °C, were investigated in detail with the aid of scanning electron microscopy in conjunction with a focused ion beam cross-section milling technique. The notch-healing results demonstrate an effective healing effect due to the predominant Al2O3 phase filling in the notch with a dense microstructure.

Tema: general: 

• Ingeniería y Ciencias Aplicadas›Ingeniería›Ingeniería Civil y Ciencia de los Materiales

Simulation of the effects of the dose rate and temperature on zircon thermoluminescence

REA Auditado

Tema: general: 

• Ingeniería y Ciencias Aplicadas›Ingeniería›Ingeniería Civil y Ciencia de los Materiales