Size and dimensionality effects in superconducting Mo thin films

Molybdenum is a low Tc, type I superconductor whose fundamental properties are poorly known. Its importance as an essential constituent of new high performance radiation detectors, the so-called transition edge sensors (TESs) calls for better characterization of this superconductor, especially in thin film form. Here we report on a study of the basic superconducting features of Mo thin films as a function of their thickness. The resistivity is found to rise and the critical temperature decreases on decreasing film thickness, as expected. More relevant, the critical fields along and perpendicular to the film plane are markedly different, thickness dependent and much larger than the thermodynamic critical field of Mo bulk. These results are consistent with a picture of type II 2D superconducting films, and allow estimates of the fundamental superconducting lengths of Mo. The role of morphology in determining the 2D and type II character of the otherwise type I molybdenum is discussed. The possible consequences of this behaviour on the performance of radiation detectors are also addressed

Super-resolution Properties of the Maxwell Fish-Eyes

In this paper we present an analysis that shows the Maxwell Fish Eye (MFE) only has super-resolution property for some particular frequencies (for other frequencies, the MFE behaves as conventional imaging lens). These frequencies are directly connected with the Schumann resonance frequencies of spherical symmetric systems. The analysis have been done using a thin spherical waveguide (two concentric spheres with constant index between them), which is a dual form of the MFE (the electrical fields in the MFE can be mapped into the radial electrical fields in the spherical waveguide). In the spherical waveguide the fields are guided inside the space between the concentric spheres. A microwave circuit comprising three elements: the spherical waveguide, the source and the receiver (two coaxial cables) is designed in COMSOL. The super-resolution is demonstrated by calculation of Scaterring (S) parameters for different position of the coaxial cables and different frequencies of the input signal.

Scriptum / Sancti Thome de Aquino super secundo sententiarum.

Marca tip. del editor en v6r (Kristeller. It.B., 281)

Low-thickness high-quality aluminum nitride films for super high frequency solidly mounted resonators

We investigate the sputter growth of very thin aluminum nitride (AlN) films on iridium electrodes for electroacoustic devices operating in the super high frequency range. Superior crystal quality and low stress films with thicknesses as low as 160 nm are achieved after a radio frequency plasma treatment of the iridium electrode followed by a two-step alternating current reactive magnetron sputtering of an aluminum target, which promotes better conditions for the nucleation of well textured AlN films in the very first stages of growth. Solidly mounted resonators tuned around 8 GHz with effective electromechanical coupling factors of 5.8% and quality factors Q up to 900 are achieved.

Dialogi quattuor super auspicato Hispania[rum] p[ri]ncipis emortuali die / Iacobo a villascusa auctore ... incipiu[n]tur.

Il. xil. de los Reyes Católicos y de la viuda del príncipe Juan, Margarita de Austria

Dialogi quattuor super auspicato Hispania[rum] p[ri]ncipis emortuali die / Iacobo a villascusa auctore ... incipiu[n]tur.

Il. xil. de los Reyes Católicos y de la viuda del príncipe Juan, Margarita de Austria

Quartus scripti Oxoniensis super sententias / [editum a fratre Joa[n]ne Duns ordinis fratrum minorum ... per ... Mauritium de Portu hiberni cum eiusdem ordinis fratrum minorum ... maxima xum diligentia emendatum].

Marca tip. xil. en colofón en 4E6r

Quartus scripti Oxoniensis super sententias / [editum a fratre Joa[n]ne Duns ordinis fratrum minorum ... per ... Mauritium de Portu hiberni cum eiusdem ordinis fratrum minorum ... maxima xum diligentia emendatum].

Marca tip. xil. en colofón en 4E6r

Sermones dominicales super Euangelia et Epistolas tam de te[m]pore q[?] de Sanctis per totum annum / editi a fratre Hugone de prato florido Ordinis predicatorum.

Fecha tomada del colofón

Melliflui deuotiq[ue] doctoris sancti Bernardi abbatis Clareualle[n]sis Cistercie[n]sis ordinis Opus preclarum suos complectens sermones de tempore, de sanctis [et] super Cantica cantico[rum], aliosq[ue] complures eius sermones et sententias ...

Pie de imp. tomado del colofón