arXiv subjects

José-María Martín-Olalla

Publications and source records attributed to José-María Martín-Olalla.

7 recordsLinked to original sources

arXiv2026

Characterizing the Carnot cycle at absolute zero: a reply to "Comment on `Proof of the Nernst theorem' "

This reply addresses a recent comment concerning the proof of the Nernst theorem. I clarify how a Carnot engine can consistently operate at $T=0$ through a continuous deformation of a cycle operating at $T>0$. By examining the limit where heat exchange with the cold reservoir vanishes, I show that the Nernst theorem ensures that the concept of temperature remains physically consistent at the absolute zero limit.

physics.class-ph↗

arXiv2026

Does classical thermodynamics need a third law? Securing the second law at absolute zero

This paper elaborates on the implications of the relationship between the Second and Third Laws and provides a comprehensive formal and historical justification for the logical redundancy of the Nernst heat theorem. By revisiting the Nernst-Einstein debate, the underlying hypotheses that lead to the traditional view of the Third Law as an independent postulate are examined. It is argued that the historical rejection of Nernst's proof -- motivated by Einstein's insistence on the practical non-performability of cycles at absolute zero -- overlooks the fact that a universal Second Law already precludes such cycles, rendering an independent Third Law an unnecessary complexity. Ultimately, the Nernst theorem is shown to be an essential consistency regulator rather than an independent physical discovery.

physics.hist-ph↗

arXiv2025

Proof of the Nernst heat theorem

The Nernst heat theorem is probed from purely thermodynamic arguments connected with the second law of thermodynamics, and alien to the vanishing of the specific heats, or to the unattainability of the zeroth isotherm. If the proof is accepted the second law of thermodynamics would extend its applicability and the third postulate of thermodynamics would be narrowed to the fact that the entropy of a finite-density, chemically homogeneous body must not be negative. -- -- Se demuestra el teorema de Nernst a partir de argumentos exclusivamente termodinámicos que se extraen del segundo principio, y que son ajenos a la anulación de los calores específicos o a la inaccesibilidad de la isoterma cero. Si se acepta la demostración, entonces el segundo principio extendería su rango de aplicabilidad y el tercer principio quedaría reducido al hecho de que la entropía de un cuerpo de densidad finita y quimicamente homogéneo no puede ser negativa.

physics.class-ph↗

arXiv2024

Ultraslow calorimetric studies of the martensitic transformation of NiFeGa alloys: detection and analysis of avalanche phenomena

We study the thermal properties of a bulk Ni55Fe19Ga26 Heusler alloy in a conduction calorimeter. At slow heating and cooling rates (1K/h), we compare as-cast and annealed samples. We report a smaller thermal hysteresis after the thermal treatment due to the stabilization of the 14M modulated structure in the martensite phase. In ultraslow experiments (40mK/h), we detect and analyze the calorimetric avalanches associated with the direct and reverse martensitic transformation from cubic to 14M phase. This reveals a distribution of events characterized by a power law with exponential cutoff $p(u) \propto u^{-\varepsilon}\exp(-u/ξ)$ where $\varepsilon\sim 2$ and damping energies $ξ=370$uJ (direct) and $ξ=27$uJ (reverse) that characterize the asymmetry of the transformation.

cond-mat.mtrl-sci↗

arXiv2024

Phase transition and polar cluster behavior above Curie temperature in ferroelectric BaTi$_{0.8}$Zr$_{0.2}$O$_3$

We study the phase transition behavior of the ferroelectric BaTi$_{0.8}$Zr$_{0.2}$O$_3$ in the paraelectric region. The temperature dependencies of thermal, polar, elastic and dielectric properties indicate the presence of local structures above the paraelectric-ferroelectric transition temperature Tc = 292 K. The non-zero remnant polarization is measured up to a characteristic temperature T* ~350 K, which coincides with the temperature where the dielectric constant deviates from Curie-Weiss law. Resonant Piezoelectric Spectroscopy shows that DC field-cooling above Tc using fields smaller than the coercive field leads to an elastic response and remnant piezoelectricity below T*, which likely corresponds to the coherence temperature associated with polar nanostructures in ferroelectrics. The observed remnant effect is attributed to the reorientation of polar nanostructures above Tc.

cond-mat.mtrl-sci↗

arXiv2019

The long term impact of Daylight Saving Time regulations in daily life at several circles of latitude

We analyze large scale (N~10000) time use surveys in United States, Spain, Italy, France and Great Britain to ascertain seasonal variations in the sleep/wake cycle and the labor cycle after daylight saving time -- summer time arrangements -- regulations have stood up for at least forty years. That is, not the usual search for short-term effects of the biannual transitions of DST but a search for how industrialized societies have responded to DST regulations. Results show that the labor cycle is equally distributed through seasons, an everyday experience which is a major outcome of DST. The sleep/wake cycle displays disturbance punctuated by solar events: sunrise, sunset and noon. Sleep onset in non-employees in a week-end -- the group more prone to free choices -- delays in summer opposing to the regulation. Yet, sleep offset in this group advances in summer, despite clock time already advanced in the spring transition. The best explanation for these findings is that size and directionality of DST regulations are close to an optimum. The role of latitude is discussed after sleep/wake cycle in Spain, Italy and United States exhibit fewer statistically significant excursions that the sleep/wake cycle in Great Britain and France, which could be indicating preference for time synchronization as latitude increases. The consequences of a seasonal regulation of clocks vs the choice of permanent summer time or permanent winter time is sketched from a previous report on human activity.

physics.soc-ph↗

arXiv2016

The winter day as a constraint for human activity in Western Europe

Time use surveys in Denmark, Spain, France, Ireland, Italy and United Kingdom are analyzed to provide start, noon and end times for the main activities of a society: labor (the focus of this preprint), sleeping and eating. Also, the location at home is analyzed. Local times are converted into mean solar times and compared to latitude. Observed trends allow to unveil the winter day as a restriction for the human activity. Alternatively, apparently large time differences set forth by clocks, becomes smaller when observed as a time distance to winter sunrise or sunset.

physics.soc-ph↗