Trap-Assisted Tunneling in the Schottky Barrier

The paper presents a new way how to calculate the currents in a Schottky barrier. The novel phenomeno-logical model extends the Shockley-Read-Hall recombi-nation-generation theory of trap-assisted tunneling. The proposed approach explains the occurrence of large leakage currents in Schottky structures on wide band semi-conductors with a high Schottky barrier (above 1 eV) and with a high density of traps. Under certain conditions, trap-assisted tunneling (TAT) plays a more important role than direct tunneling

Magnetic and structural properties of the iron silicide superconductor LaFeSiH

The magnetic and structural properties of the recently discovered pnictogen/chalcogen-free superconductor LaFeSiH ($T_c\simeq10$~K) have been investigated by $^{57}$Fe synchrotron M{\"o}ssbauer source (SMS) spectroscopy, x-ray and neutron powder diffraction and $^{29}$Si nuclear magnetic resonance spectroscopy (NMR). No sign of long range magnetic order or local moments has been detected in any of the measurements and LaFeSiH remains tetragonal down to 2 K. The activated temperature dependence of both the NMR Knight shift and the relaxation rate $1/T_1$ is analogous to that observed in strongly overdoped Fe-based superconductors. These results, together with the temperature-independent NMR linewidth, show that LaFeSiH is an homogeneous metal, far from any magnetic or nematic instability, and with similar Fermi surface properties as strongly overdoped iron pnictides. This raises the prospect of enhancing the $T_c$ of LaFeSiH by reducing its carrier concentration through appropriate chemical substitutions. Additional SMS spectroscopy measurements under hydrostatic pressure up to 18.8~GPa found no measurable hyperfine field

Lattice dynamics of endotaxial silicide nanowires

Self-organized silicide nanowires are considered as main building blocks of future nanoelectronics and have been intensively investigated. In nanostructures, the lattice vibrational waves (phonons) deviate drastically from those in bulk crystals, which gives rise to anomalies in thermodynamic, elastic, electronic, and magnetic properties. Hence, a thorough understanding of the physical properties of these materials requires a comprehensive investigation of the lattice dynamics as a function of the nanowire size. We performed a systematic lattice dynamics study of endotaxial FeSi$_2$ nanowires, forming the metastable, surface-stabilized $\alpha$-phase, which are in-plane embedded into the Si(110) surface. The average widths of the nanowires ranged from 24 to 3 nm, their lengths ranged from several $\mu$m to about 100 nm. The Fe-partial phonon density of states, obtained by nuclear inelastic scattering, exhibits a broadening of the spectral features with decreasing nanowire width. The experimental data obtained along and across the nanowires unveiled a pronounced vibrational anisotropy that originates from the specific orientation of the tetragonal $\alpha$-FeSi$_2$ unit cell on the Si(110) surface. The results from first-principles calculations are fully consistent with the experimental data and allow for a comprehensive understanding of the lattice dynamics of endotaxial silicide nanowires.Comment: 9 pages, 7 figures, 3 table

Complete Set of Elastic Moduli of a Spin-Crossover Solid: Spin-State Dependence and Mechanical Actuation

Molecular spin crossover complexes are promising candidates for mechanical actuation purposes. The relationships between their crystal structure and mechanical properties remain, however, not well understood. In this study, combining high pressure synchrotron Xray diffraction and nuclear inelastic scattering measurements, we assessed the effective macroscopic bulk modulus (11.5 ± 2.0 GPa), Young’s modulus (10.9 ± 1.0 GPa) and Poisson’s ratio (0.34 ± 0.04) of the spin crossover complex [FeII(HB(tz)3)2] (tz = 1,2,4-triazol-1-yl) in its low spin state. Crystal structure analysis revealed a pronounced anisotropy of the lattice compressibility, which was correlated with the difference in spacing between the molecules in different crystallographic directions. Switching the molecules from the low spin to the high spin state leads to a remarkable drop of the Young’s modulus to 7.1 ± 0.5 GPa, which was also assessed in thin film samples by means of micromechanical measurements. These results are in agreement with the high cooperativity of the spin crossover in this compound and highlight its application potential in terms of recoverable stress (21 ± 1 MPa) and work density (15 ± 6 mJ/cm3)

Effects and implementation of a mindfulness and relaxation app for patients with cancer: Mixed methods feasibility study

Background: Cancer diagnosis and cancer treatment can cause high levels of distress, which is often not sufficiently addressed in standard medical care. Therefore, a variety of supportive nonpharmacological treatments have been suggested to reduce distress in patients with cancer. However, not all patients use these interventions because of limited access or lack of awareness. To overcome these barriers, mobile health may be a promising way to deliver the respective supportive treatments. Objective: The aim of this study is to evaluate the effects and implementation of a mindfulness and relaxation app intervention for patients with cancer as well as patients’ adherence to such an intervention. Methods: In this observational feasibility study with a mixed methods approach, patients with cancer were recruited through the web and through hospitals in Switzerland. All enrolled patients received access to a mindfulness and relaxation app. Patients completed self-reported outcomes (general health, health-related quality of life, anxiety, depression, distress, mindfulness, and fear of progression) at baseline and at weeks 4, 10, and 20. The frequency of app exercise usage was gathered directly through the app to assess the adherence of patients. In addition, we conducted interviews with 5 health professionals for their thoughts on the implementation of the app intervention in standard medical care. We analyzed patients’ self-reported outcomes using linear mixed models (LMMs) and qualitative data with content analysis. Results: A total of 100 patients with cancer (74 female) with a mean age of 53.2 years (SD 11.6) participated in the study, of which 25 patients used the app regularly until week 20. LMM analyses revealed improvements in anxiety (P=.04), distress (P<.001), fatigue (P=.01), sleep disturbance (P=.02), quality of life (P=.03), and mindfulness (P<.001) over the course of 20 weeks. Further LMM analyses revealed a larger improvement in distress (P<.001), a moderate improvement in anxiety (P=.001), and a larger improvement in depression (P=.03) in patients with high levels of symptoms at baseline in the respective domains. The interviews revealed that the health professionals perceived the app as a helpful addition to standard care. They also made suggestions for improvements, which could facilitate the implementation of and adherence to such an app. Conclusions: This study indicates that a mindfulness and relaxation app for patients with cancer can be a feasible and effective way to deliver a self-care intervention, especially for highly distressed patients. Future studies should investigate if the appeal of the app can be increased with more content, and the effectiveness of such an intervention needs to be tested in a randomized controlled trial