Search

The 12442 compounds are a recently discovered family of iron-based superconductors, that share several features with the cuprates due to their strongly anisotropic structure, but are so far poorly understood. Here, we report on the gap structure and anisotropy of RbCa2(Fe1−xNix)4As4F2 single crystals, investigated by a combination of directional point-contact Andreev-reflection spectroscopy and coplanar waveguide resonator measurements. Two gaps were identified, with clear signatures of d-wave-like nodal structures which persist upon Ni doping, well described by a two-band d − d state with symmetry-imposed nodes. A large London penetration depth anisotropy was revealed, weakly dependent on temperature and fully compatible with the d − d model. [ABSTRACT FROM AUTHOR]

Single crystal X‐ray crystallographic analysis of 7,8‐dihydro‐6H‐[1,4]diazepino[1,2‐a:4,3‐a′]diindole‐14,15‐dione (propano‐bridged indigo [PBI]) reveals the presence of two homopolar intermolecular dihydrogen C–H···H–C interactions of distances 2.38 and 2.89 Å. Hirshfeld surface analysis indicates a significant contribution of C–H···H–C interactions (49%) to the total molecular contact surface. Theoretical analysis of the topology of electron density reveals the existence of two closed shell dihydrogen interactions per dimer. The values of the AIM charges on the H⋯H interacting atoms are similar (0.172). The calculated dihydrogen interaction energy is found to be significant (3.76 kcal mol−1). London dispersion forces are the dominant contributor to the homopolar C–H···H–C interactions. [ABSTRACT FROM AUTHOR]

Non-covalent aryl–aryl interactions for the molecular structures of three 1,2-diaryltetramethyldisilanes X5C6–(SiMe2)2–C6Y5 (X ≠ Y; X, Y = H, F, Cl) were studied by single crystal X-ray and gas electron diffraction as well as by SAPT calculations. Aryl–aryl interactions cause all to adopt exclusively rather untypical eclipsed syn-conformers in the gas phase, and C6F5–(SiMe2)2–C6Cl5 also in the solid state. [ABSTRACT FROM AUTHOR]

• Study of superconducting properties in topological candidate BaBi 3 is reported. • Determination of magnetic penetration depth from reversible magnetization. • Pinning force scaling indicates vortex pinning by volume Ginzburg-Landau parameter variations. • Vortex pinning energies using Anderson-Kim model are provided. Hysteresis and magnetic relaxation measurements were performed on single crystals of BaBi 3 , which is an intermetallic compound exhibiting superconductivity with a critical temperature (T c) of 5.9 K. The London penetration depth (λ) was determined to be 130 nm, and the coherence length (ξ) was estimated to be 13 nm. The critical current density (J c) was found remarkably low, measuring 20,000 A/cm2 under self-field conditions at 1.8 K. Analysis of the pinning forces suggests vortex pinning by crystalline defects associated with volume Δ k (variations in the Ginzburg-Landau parameter). The relaxation rate follows the Anderson-Kim model, and the pinning energies range from 1600 K at 0.02 T to 500 K at 0.5 T. Our study aims to advance our understanding of the connection between intrinsic superconducting properties and vortex behavior in intermetallic materials characterized by low thermal fluctuations. [ABSTRACT FROM AUTHOR]

We report on the superconductive paired states in TbPdBi, β-type FeSe and CaSn 3 single crystals through temperature dependence of magnetic penetration depth analysis down to 0.040 K. For half-Heusler TbPdBi, in ultra-low temperature region we traced the T3 power-law behavior of penetration depth indicating the nodeless topological superconductivity with anisotropic gap structure which was confirmed with the analysis of superfluid density. That highlights the role of thermally activated quasi-particles in the pairing mechanism of TBPdBi for which the variation of Δλ(T) wanders off the renown quadratic behavior of penetration depth. In FeSe the contribution of London depth was described with a power law (n ≈ 2.4) and the superfluid density fitted well with two-band d + d model in which the values of both gaps are substantially smaller than the gap size expected by the isotropic BCS model, due to the nodeless anisotropic gap symmetry. In CaSn 3 , temperature variation of magnetic penetration depth exhibited linear behavior which is ascribed to the topologically nontrivial electronic states. Also, fitting the results of superfluid density exhibited features of multiband pairing allowing the nodal gap in the electronic states which is in good agreement with the expectation of London penetration depth. The complex superconducting order parameter is suggestive of two-dimensional spin singlet or mixing singlet-triplet pairing states behind the signatures of superconductivity in CaSn 3. The mechanisms of pairing symmetry uncovered by the temperature dependence of penetration depth study of TbPdBi, FeSe and CaSn 3 meet the requirements for topological superconductivity. • For first time, topologically nontrivial pairing states of TbPdBi, Fese and CaSn 3 have been studied. • Ultra-low temperature of magnetic London penetration depth and superfluid density has been thoroughly investigated. • Superconducting gaps of these materials have also been measured. [ABSTRACT FROM AUTHOR]