How experimentally to detect a solitary superconductivity in dirty ferromagnet-superconductor trilayers?

We theoretically study the proximity effect in the thin-film layered ferromagnet (F) - superconductor (S) heterostructures in F$_1$F$_2$S design. We consider the boundary value problem for the Usadel-like equations in the case of so-called "dirty" limit. The "latent" superconducting pairing interaction in F layers taken into account. The focus is on the recipe of experimental preparation the state with so-called solitary superconductivity. We also propose and discuss the model of the superconducting spin valve based on F$_1$F$_2$S trilayers in solitary superconductivity regime

Structure and phase transition in BaThO3: A combined neutron and synchrotron X-ray diffraction study

The structure of BaThO3, obtained by solid state synthesis, was refined for the first time by the Rietveld method using a combination of synchrotron X-ray and neutron powder diffraction data. BaThO3 has an orthorhombic structure at room temperature, in space group Pbnm with a = 6.3491(5), b = 6.3796(4) and c = 8.9907(7) Å. Heating BaThO3 to above 700 °C results in a continuous transition to a second orthorhombic structure, in space group Ibmm, demonstrated by both in situ neutron and synchrotron X-ray powder diffraction measurements. The coefficient of volumetric thermal expansion for BaThO3 is determined to be 1.04 x 10-5 oC-1 from 50 to 625 oC (Pbnm phase), and 9.43 x 10-6 oC-1 from 800 to 1000 oC (Ibmm phase). BaThO3 was found to decompose upon exposure to atmospheric moisture resulting in the formation of ThO2. The thermal expansion of ThO2, which invariably co-exists with BaThO3, is also described.Australian Synchrotron Australian Research Council2019-12-1

Structure and phase transition in BaThO3: A combined neutron and synchrotron X-ray diffraction study

The structure of BaThO3, obtained by solid state synthesis, was refined for the first time by the Rietveld method using a combination of synchrotron X-ray and neutron powder diffraction data. BaThO3 has an orthorhombic structure at room temperature, in space group Pbnm with a = 6.3491(5), b = 6.3796(4) and c = 8.9907(7) Å. Heating BaThO3 to above 700 °C results in a continuous transition to a second orthorhombic structure, in space group Ibmm, demonstrated by both in situ neutron and synchrotron X-ray powder diffraction measurements. The coefficient of volumetric thermal expansion for BaThO3 is determined to be 1.04 x 10-5 oC-1 from 50 to 625 oC (Pbnm phase), and 9.43 x 10-6 oC-1 from 800 to 1000 oC (Ibmm phase). BaThO3 was found to decompose upon exposure to atmospheric moisture resulting in the formation of ThO2. The thermal expansion of ThO2, which invariably co-exists with BaThO3, is also described.Australian Synchrotron Australian Research Counci

A Manifestation of Latent Superconductivity in Ferromagnet via a Proximity Effect in FS Structures

AbstractWe theoretically study the proximity effect in the thin-film layered ferromagnet (F) - super-conductor (S) heterostructures of two types (F1SF2 and F1F2S). We consider the boundary value problem for the Usadel-like equations in the case of so-called “dirty” limit. The “latent” superconducting pairing interaction in F layers taken into account. It is shown that the inter-electronic interaction essentially influences on the critical properties of the both trilayers. The appearance of the solitary superconductivity is predicted for the F1SF2 and F1F2S systems

Magnetic structure of triangular lattice compound Tb2Ni0.90Si2.94

AlB 2-type ternary intermetallic compound Tb 2Ni 0.90Si 2.94 (space group P 6=mmm, hP 3, No. 191) was reported to exhibit spin freezing behaviour of the ferromagnetic clusters present in the system below T f = 9:9 K, along with the presence of spatially limited antiferromagnetic phase. In this work, on the basis of variable temperature zero-field neutron diffraction measurements, we have shown that the antiferromagnetic phase transition occurs for the compound below T N ~13 K. Neutron diffraction study indicates ab-plane non-collinear sine-modulated antiferromagnetic ordering of the system with wave vectors of k 1 = [±1/6, ±1/6, 0] and k 2 = [±1/3, ±1/3, 0] down to 1.7 K. The weak and diffuse nature of the magnetic Bragg peaks along with limited coherence length further confirm the short-range nature of the antiferromagnetic phase in this compound.</p

Crystal chemistry of vanadium-bearing Ellestadite waste forms

Vanadate ellestadites Ca10(SiO4)x(VO4)6–2x(SO4)xCl2, serving as prototype crystalline matrices for the fixation of pentavalent toxic metals (V, Cr, As), were synthesized and characterized by powder X-ray and neutron diffraction (PXRD and PND), electron probe microanalysis (EPMA), Fourier transform infrared spectroscopy (FTIR), and solid-state nuclear magnetic resonance (SS-NMR). The ellestadites 0.19 < x < 3 adopt the P63/m structure, while the vanadate endmember Ca10(VO4)6Cl2 is triclinic with space group P1̅. A miscibility gap exists for 0.77 < x < 2.44. The deficiency of Cl in the structure leads to short-range disorder in the tunnel. Toxicity characteristic leaching testing (TCLP) showed the incorporation of vanadium increases ellestadite solubility, and defined a waste loading limit that should not exceed 25 atom % V to ensure small release levels

Cation disorder in NaW2O6+δ·nH2−zO post-ion exchange with K, Rb, Sr, and Cs

The structure of the defect pyrochlore NaW(2)O(6+delta)center dot nH(2-z)O after ion exchange with K, Rb, Sr or Cs for Na has been investigated using thermal analysis, solid-state nuclear magnetic resonance, laboratory X-ray and neutron diffraction methods. Neutron diffraction studies show that both the A-type cations (Na(+), K(+), Rb(+), and/or Cs(+)) and the water molecules reside within the channels that form in the 111 direction of the W(2)O(6) framework and that these strongly interact. The analytical results suggest that the water and A-type cations compete for space in the tunnels within the W(2)O(6) pyrochlore framework, with the total number of water molecules and cations being approximately constant in the six samples investigated. The interplay between the cations and water explains the non-linear dependence of the a lattice parameter on the choice of cation. It appears that the ion-exchange capacity of the material will be controlled by the amount of water initially present in the sample

Phase Behaviour and Mixed Ionic-Electronic Conductivity of Ba4Sb2O9

The 6H-type perovskite phase Ba4Sb2O9, which decomposes in air below 600 K, is found to survive to room temperature in a CO2-free atmosphere. It shows substantial mixed protonic, oxide ionic and electronic conductivity. However, compared to Ba4 Nb2 O9 and Ba4 Ta2 O9 , Ba4Sb2O9 shows higher ionic conductivity due to the relatively easy reducibility of Sb5+, but lower electronic conductivity due to the predominantly n-type conductivity provided by the Sb5+/Sb3+ redox couple which leads to reduced hole concentration under oxidising conditions. Variable temperature synchrotron x-ray and neutron powder diffraction studies carried out in tu under controlled atmospheres reveal a strong monoclinic distortion below 1150 K. The hexagonal → monoclinic transition is slow, does not show second-order behaviour, is strongly dependent on atmosphere, and coincides with the loss of ∼0.4 molecules of H2O per formula unit of Ba4Sb2O9. All of this suggests an important structural role for protons or hydroxide ions in the monoclinic phase