SearcharxivSearch

arXiv subjects

Tetsu Ichitsubo

Publications and source records attributed to Tetsu Ichitsubo.

3 recordsLinked to original sources

When dissipative steady states admit thermodynamic occupation laws

Non-equilibrium steady states (NESSs) generally lack thermodynamic occupation laws because finite stationary circulation and a globally exact rate-ratio field cannot coexist for the same Markov generator. Here we construct a sector-separated geometry that overcomes this incompatibility without arresting dissipation. Entropy-production exposure-and-separation excludes the entropy-producing state~$0$ from the conditional occupation manifold while retaining it in the dissipative full graph; physical returns $i\to0\to0^\ast$ become effectively Markovian in the strong-bias/rapid-reset (SR) limit. For a thermodynamically complete conditional manifold, autonomous redistribution (AR) eliminates residual futile circulation, making the rate-ratio one-form exact. Thermodynamic calibration gives $X_i=\beta(\Delta\mu- \mathcal F_i^{\mathrm{cost}})$ and $p_i=e^{X_i}/Z_\mathcal{C}$, with $Z_\mathcal{C}=1+\sum_i e^{X_i}$. Full-graph probabilities factorize exactly as $P_\alpha=(1-P_0)p_\alpha$. In the SR limit, the kinetic factor tends to unity while $p_\alpha\to e^{X_\alpha}/Z_\mathcal C$, yielding $P_\alpha\to p_\alpha$ while finite dissipation persists. Near AR, integrability is lost linearly in residual cycle current whereas dissipation begins quadratically. In the binary zero-cycle-rank limit, occupation redistributes autonomously under maintained $\Delta\mu$ bias, yielding the inverted Fermi--Dirac law, which is applied to thermal smearing in quantum-dot lasers. The framework provides constructive acquisition conditions and failure diagnostics for thermodynamic occupation laws in dissipative NESSs.

cond-mat.stat-mech

Non-stoichiometry in SnS: How it affects thin-film morphology and electrical properties

Tin sulfide (SnS) has garnered much attention as a promising material for various applications, including solar cells and thermoelectric devices, owing to its favorable optical and electronic properties and the abundant and nontoxic nature of its constituent elements. Herein, we investigated the effect of non-stoichiometry on the morphology and electrical properties of SnS thin films. Using a unique sputtering technique with a sulfur plasma supply, SnS films with precise sulfur content control, [S]/([Sn] + [S]) (xS) ranging from 0.47 to 0.51, were fabricated. Systematic characterization revealed that non-stoichiometry on the S-rich side led to a marked increase in the carrier density of p-type conduction, which was attributed to the formation of intrinsic acceptor-type defects. In contrast, non-stoichiometry on the S-poor side hardly affects the p-type electrical properties, apparently because of the self-compensation between the intrinsic acceptor- and donor-type defects. In addition, non-stoichiometry has been identified as the cause of thin-film morphological changes, with non-stoichiometric films exhibiting rough and porous surfaces. Achieving a stoichiometric composition results in smooth and dense thin-film morphologies, which are crucial for optimizing SnS thin films for device applications. These findings underscore the importance of compositional control for tailoring the morphology and electrical behavior of SnS, paving the way for more efficient SnS-based devices.

cond-mat.mtrl-sci

Structural and Dynamical Changes in a Gd-Co Metallic Glass by Cryogenic Rejuvenation

To experimentally clarify the changes in structural and dynamic heterogeneities in a metallic glass (MG), Gd65Co35, by rejuvenation with a temperature cycling (cryogenic rejuvenation), high-energy x-ray diffraction (HEXRD), anomalous x-ray scattering (AXS), and inelastic x-ray scattering (IXS) experiments were carried out. By a repeated temperature change between liquid N2 and room temperatures 40 times, tiny but clear structural changes are observed by HEXRD even in the first neighboring range. Partial structural information obtained by AXS reveals that slight movements of the Gd and Co atoms occur in the first- and second-neighboring shells around the central Gd atom. The concentration inhomogeneity in the nm size drastically increases for the Gd atoms by the temperature cycling, while the other heterogeneities are negligible. A distinct change was detected in a microscopic elastic property by IXS: The width of longitudinal acoustic excitation broadens by about 20%, indicating an increase of the elastic heterogeneity of this MG by the thermal treatments. These static and dynamic results explicitly clarify the features of the cryogenic rejuvenation effect experimentally.

cond-mat.mtrl-sci