Half-Heusler topological insulators

Ternary semiconducting or metallic half-Heusler compounds with an atomic composition 1:1:1 are widely studied for their flexible electronic properties and functionalities. Recently, a new material property of half-Heusler compounds was predicted based on electronic structure calculations: the topological insulator. In topological insulators, the metallic surface states are protected from impurity backscattering due to spin-momentum locking. This opens up new perspectives in engineering multifunctional materials. In this article, we introduce half Heusler materials from the crystallographic and electronic structure point of view. We present an effective model Hamiltonian from which the topological state can be derived, notably from a non-trivial inverted band structure. We discuss general implications of the inverted band structure with a focus on the detection of the topological surface states in experiments by reviewing several exemplary materials. Special attention is given to superconducting half-Heusler materials, which have attracted ample attention as a platform for non-centrosymmetric and topological superconductivity.Comment: Published on MRS Bulletin, the focus issue on topological insulators. 20 Pages, 7 figures and 1 tabl

Direct observation of a Fermi liquid-like normal state in an iron-pnictide superconductor

There are two prerequisites for understanding high-temperature (high-T$_c$) superconductivity: identifying the pairing interaction and a correct description of the normal state from which superconductivity emerges. The nature of the normal state of iron-pnictide superconductors, and the role played by correlations arising from partially screened interactions, are still under debate. Here we show that the normal state of carefully annealed electron-doped BaFe$_{2-x}$Co$_{x}$As$_2$ at low temperatures has all the hallmark properties of a local Fermi liquid, with a more incoherent state emerging at elevated temperatures, an identification made possible using bulk-sensitive optical spectroscopy with high frequency and temperature resolution. The frequency dependent scattering rate extracted from the optical conductivity deviates from the expected scaling $M_{2}(\omega,T)\propto(\hbar\omega)^{2}+(p\pi k_{B}T)^{2}$ with $p\approx$ 1.47 rather than $p$ = 2, indicative of the presence of residual elastic resonant scattering. Excellent agreement between the experimental results and theoretical modeling allows us to extract the characteristic Fermi liquid scale $T_{0}\approx$ 1700 K. Our results show that the electron-doped iron-pnictides should be regarded as weakly correlated Fermi liquids with a weak mass enhancement resulting from residual electron-electron scattering from thermally excited quasi-particles.Comment: 6+9pages, 3+9 figures To be published in Scientific Report

Interaction between counter-propagating quantum Hall edge channels in the 3D topological insulator BiSbTeSe2_2

The quantum Hall effect is studied in the topological insulator BiSbTeSe$_2$. By employing top- and back-gate electric fields at high magnetic field, the Landau levels of the Dirac cones in the top and bottom topological surface states can be tuned independently. When one surface is tuned to the electron-doped side of the Dirac cone and the other surface to the hole-doped side, the quantum Hall edge channels are counter-propagating. The opposite edge mode direction, combined with the opposite helicities of top and bottom surfaces, allows for scattering between these counter-propagating edge modes. The total Hall conductance is integer valued only when the scattering is strong. For weaker interaction, a non-integer quantum Hall effect is expected and measured

4π4\pi periodic Andreev bound states in a Dirac semimetal

Electrons in a Dirac semimetals possess linear dispersion in all three spatial dimensions, and form part of a developing platform of novel quantum materials. Bi$_{1-x}$Sb$_x$ supports a three-dimensional Dirac cone at the Sb-induced band inversion point. Nanoscale phase-sensitive junction technology is used to induce superconductivity in this Dirac semimetal. Radio frequency irradiation experiments reveal a significant contribution of 4$\pi$-periodic Andreev bound states to the supercurrent in Nb-Bi$_{0.97}$Sb$_{0.03}$-Nb Josephson junctions. The conditions for a substantial $4\pi$ contribution to the supercurrent are favourable because of the Dirac cone's topological protection against backscattering, providing very broad transmission resonances. The large g-factor of the Zeeman effect from a magnetic field applied in the plane of the junction, allows tuning of the Josephson junctions from 0 to $\pi$ regimes.Comment: Supplementary information is include

The Perspectives of Healthcare Professionals and Managers on Patient Involvement in Care Pathway Development:A Discourse Analysis

Background: The WHO advocates patient and public involvement as an ethical imperative, due to the value of the lived experience of patients. A deeper understanding of the shared meanings and underlying beliefs of healthcare professionals and managers for and against including patients in care pathway development. Objective: To explore the considerations of healthcare professionals and managers on the involvement of patients and public in care pathway development. Methods: In a medical rehabilitation centre we conducted a single case study that was part of a 2-year action research programme on blended care pathway development. Following 14 semistructured interviews with healthcare professionals and managers, we analysed their discourses on the value of patient involvement as well as the potential threats and opportunities. Results: We identified four discourses. Patient as expert frames involvement as relevant, as adding new perspectives and as required to fully understand the patient's needs. Skills and representation is based on the construct that obtaining valuable insights from patients requires certain skills and competences. Self-protection focusses on personal, interprofessional objections to patient involvement. Professional knows best reveals expertise-related reasons for avoiding or postponing involvement. Conclusion: These discourses explain why patient and public involvement in care pathway development is sometimes postponed, limited in scope and level of participation, and/or avoided. The following strategies might minimise the paralysing effect of these discourses: strengthen the capabilities of all stakeholders involved; use a mix of complementary techniques to gain involvement in distinct phases of care pathway development; and create/facilitate a safe environment. Put together, these strategies would foster ongoing, reciprocal learning that could enhance patient involvement. Patient or Public Contribution: This study belonged to an action research programme on blended care pathway development (developing an integrated, coordinated patient care plan that combines remote, digital telehealth applications, self-management tools and face-to-face care). Multidisciplinary teams took a quality collaborative approach to quality improvement (considering patients as stakeholders) to develop 11 blended care pathways. Although professionals and managers were instructed to invite patients onto their teams and to attend care pathway design workshops, few teams (3/11) actually did. Unravelling why this happened will help improve patient and public involvement in care pathway development.</p

Type-I superconductivity in PdTe2_2 probed by μ\muSR

The Dirac semimetal PdTe$_2$ was recently reported to be a type-I superconductor with $T_c = 1.64$ K and a critical field $\mu_0H_c = 13.6$ mT. Since type-I superconductivity is unexpected for binary compounds, we have conducted muon spin rotation experiments to probe the superconducting phase on the microscopic scale via its intermediate state. For crystals with a finite demagnetization factor, $N$, the intermediate state forms in applied fields $(1-N)H_c < H_a < H_c$. We have carried out transverse field muon spin rotation measurements on a thin disk-like crystal with the field perpendicular to ($N_{\perp}=0.86$) and in the plane ($N_{\parallel}=0.08$) of the disk. By analysing the $\mu$SR signal we find that the volume fraction of the normal domains grows quasi-linearly with applied field at the expense of the Meissner domain fraction. This then provides solid evidence for the intermediate state and type-I superconductivity in the bulk of PdTe$_2$

Spiritual care by nurses in curative oncology:a national, multicenter, mixed method study

Introduction: Spiritual care by nurses is often linked to palliative and terminal care. It is hardly known whether SC is also considered vital among nurses who care for patients who are treated with curative intent. Therefore, we have explored the level of and the experiences with spiritual care by nurses in curative cancer care.Methods: In this mixed-method study, nurses were recruited in eight hospitals in the Netherlands. A spirituality scale, a spiritual care competence scale and five questions on spiritual care were completed by 57 participants. Afterwards, the scores were quantitatively analyzed. Because of data saturation, qualitative analysis was limited to 31 semi-structured interviews, using content analysis.Results: The great majority of nurses indicated on the questionnaire that they frequently provide spiritual care. However, in interviews, the nurses described few examples of spiritual care. Nurses also indicated that they had not learned so much in providing spiritual care in their educational program; rather, they had learned it in clinical practice.Conclusions: As the questionnaire could be liable to socially desirable responding, we based our conclusions on the qualitative data, and concluded that spiritual care was rather modest among the nurses providing curative care in this stud

Weak antilocalization induced by Se substitution in layered BiCh2_2-based (Ch = S, Se) superconductors LaO1−x_{1-x}Fx_xBiS2−y_{2-y}Sey_y

We report transport properties for layered BiCh2-based (Ch = S, Se) superconductors LaO1-xFxBiS2-ySey (x = 0.2, 0.5, y = 0-1.05) and the observation of weak antilocalization (WAL). Electrical resistivity and Hall coefficients for the Se-poor samples increase with decreasing temperature. The increase becomes less pronounced with increasing Se concentration indicating a loss of insulating behavior. Interestingly, the moderately Se-substituted samples exhibit metallic behavior in the high-temperature region and a weak increase in the resistivity in the low-temperature regions, which indicates the existence of carrier localization. The heavily Se-substituted compounds show metallic behavior in the entire-temperature region. Sign changes of the Hall coefficients are observed for the x = 0.2 samples, which possibly is related to a charge-density wave (CDW). Magnetoresistance measurements indicate that WAL is realized in the heavily Se-substituted systems. The WAL behavior is weakened by the changes in F and Se concentrations. A crossover state of the WAL and WL emerges around the moderately F-doped and Se-free LaO0.8F0.2BiS2. The change of the resistivity behavior by the F and Se substitution clearly correlates to the difference of the magnetoconductance. Moreover, the localization regions of the WAL-WL crossover and weak WAL states are possibly associated with the CDW. We propose that the BiCh2-based system is a good platform for studying relationship between WAL, superconductivity, and electronic ordering because those states are tunable by element substitutions with bulk single crystals

Measurement Properties of the Dutch Multifactor Fatigue Scale in Early and Late Rehabilitation of Acquired Brain Injury in Denmark

Fatigue is a major issue in neurorehabilitation without a gold standard for assessment. The purpose of this study was to evaluate measurement properties of the five subscales of the self-report questionnaire the Dutch Multifactor Fatigue Scale (DMFS) among Danish adults with acquired brain injury. A multicenter study was conducted (N = 149, 92.6% with stroke), including a stroke unit and three community-based rehabilitation centers. Unidimensionality and measurement invariance across rehabilitation settings were tested using confirmatory factor analysis. External validity with Depression Anxiety Stress Scales (DASS-21) and the EQ-5D-5L was investigated using correlational analysis. Results were mixed. Unidimensionality and partial invariance were supported for the Impact of Fatigue, Mental Fatigue, and Signs and Direct Consequences of Fatigue, range: RMSEA = 0.07–0.08, CFI = 0.94–0.99, ω = 0.78–0.90. Coping with Fatigue provided poor model fit, RMSEA = 0.15, CFI = 0.81, ω = 0.46, and Physical Fatigue exhibited local dependence. Correlations among the DMFS, DASS-21, and EQ-5D-5L were in expected directions but in larger magnitudes compared to previous research. In conclusion, three subscales of the DMFS are recommended for assessing fatigue in early and late rehabilitation, and these may facilitate the targeting of interventions across transitions in neurorehabilitation. Subscales were strongly interrelated, and the factor solution needs evaluation.</p