We report the successful synthesis of a new 4\(d\) based polycrystalline inverse Heusler alloy Fe\(_2\)RuGe by an arc melting process and have studied in detail its structural, magnetic and transport ...properties complemented with first principle calculations. X-ray and neutron diffraction, Extended X-ray Absorption Fine Structure and \(^{57}\)Fe M\"{o}ssbauer spectroscopic studies confirm the single phase nature of the system where the Fe and Ru atoms are randomly distributed in the 4\(c\) and 4\(d\) Wyckoff positions in a ratio close to 50:50. The formation of the disordered structure is also confirmed by the theoretical energy minimization calculation. Despite the random cross-site disorder of Fe and Ru atoms, magnetic measurements suggest not only a high Curie temperature of \(\sim\)860\,K, but also a large saturation magnetic moment \(\sim\)4.9\,\(\mu_B\) per formula unit at 5\,K, considerably exceeding the theoretical limit (4\,\(\mu_B\) per formula unit) predicted by the Slater-Pauling rule. Only a few Fe-based inverse Heusler alloys are known to exhibit such high Curie temperatures. Neutron diffraction analysis coupled with the isothermal magnetization value indicates that the magnetic moments in Fe\(_2\)RuGe are associated with Fe-atoms only, which is also confirmed by M\"ossbauer spectrometry. Interestingly, in comparison to the cubic or hexagonal phase of the parent compound, Fe\(_3\)Ge, the Curie temperature of Fe\(_2\)RuGe has increased significantly despite the substitution of the nonmagnetic, yet isoelectronic element Ru in this structurally disordered compound. Our theoretical calculation reveals that the large Fe moment (\(\sim2.8\mu_B\)/Fe) on the 4\(b\) site can be attributed to a charge transfer from this Fe site towards its Ru neighbours. Such a substantial increase in magnetic moment due to electron charge transfer has not previously been reported in a Heusler alloy system.
Pure spin current has transfigured the energy-efficient spintronic devices and it has the salient characteristic of transport of the spin angular momentum. Spin pumping is a potent method to generate ...pure spin current and for its increased efficiency high effective spin-mixing conductance (Geff) and interfacial spin transparency (T) are essential. Here, a giant T is reported in Sub/W(t)/Co20Fe60B20(d)/SiO2(2 nm) heterostructures in \beta-tungsten (\beta-W) phase by employing all-optical time-resolved magneto-optical Kerr effect technique. From the variation of Gilbert damping with W and CoFeB thicknesses, the spin diffusion length of W and spin-mixing conductances are extracted. Subsequently, T is derived as 0.81 \pm 0.03 for the \beta-W/CoFeB interface. A sharp variation of Geff and T with W thickness is observed in consonance with the thickness-dependent structural phase transition and resistivity of W. The spin memory loss and two-magnon scattering effects are found to have negligible contributions to damping modulation as opposed to spin pumping effect which is reconfirmed from the invariance of damping with Cu spacer layer thickness inserted between W and CoFeB. The observation of giant interfacial spin transparency and its strong dependence on crystal structures of W will be important for pure spin current based spin-orbitronic devices.
The pursuit of efficient spin-polarization in quaternary Heusler alloys with the general formula \(XX'YZ\) (where X, \(X'\), and Y are transition metals and Z is a p-block element), has been a ...subject of significant scientific interest. While previous studies shows that isoelectronic substitution of 4d element in place of 3d element in quaternary Heusler alloy, improves the half-metallic ferromagnetic characteristics, our research on the quaternary Heusler alloy NiRuMnSn reveals a strikingly different scenario. In this study, we present a detailed structural analysis of the material using X-ray absorption fine structure (EXAFS) and neutron diffraction (ND) techniques, which confirms the formation of a single-phase compound with 50:50 site disorder between Ni/Ru atoms at 4c/4d sites. Contrary to expectations, our DFT calculations suggests a considerable decrease in spin-polarization even in the ordered structure. Additionally, we report on the compound's exceptional behavior, displaying a rare re-entrant spin glass property below \(\sim\)60 K, a unique and intriguing feature for quaternary Heusler-type compounds.
In this work, we report the successful synthesis of a Fe-based novel half-metallic quaternary Heusler alloy FeMnVGa and its structural, magnetic and transport properties probed through different ...experimental methods and theoretical technique. Density functional theory (DFT) calculations performed on different types of structure reveal that Type-2 ordered structure (space group: F-43m, Ga at 4a, V at 4b, Mn at 4c and Fe at 4d) possess minimum energy among all the ordered variants. Ab-initio simulations in Type 2 ordered structure further reveal that the compound is half-metallic ferromagnet (HMF) having a large spin-polarization (89.9 %). Neutron diffraction reveal that the compound crystalizes in disordered Type-2 structure (space group: Fm-3m) in which Ga occupy at 4a, V at 4b and Fe/Mn occupy 4c/4d sites with 50:50 proportions. The structural disorder is further confirmed by X-ray diffraction (XRD), extended X-ray absorption fine structure (EXAFS),57Fe Mossbauer spectrometry results and DFT calculations. Magnetisation studies suggest that the compound orders ferromagnetically below TC ~ 293 K and the saturation magnetization follows Slater-Pauling rule. Mossbauer spectrometry, along with neutron diffraction suggest that Mn is the major contributor to the total magnetism in the compound consistent with the theoretical calculations. First principle calculations indicate that spin-polarization remain high (81.3 %) even in the presence of such large atomic disorder. The robustness of the HMF property in presence of disorder is a quite unique characteristic over other reported HMF in literature and make this compound quiet promising for spintronics applications.
Solvation dynamics in the two partially folded states (I
S′ and I
S″) of a protein, cytochrome
C′ has been studied using picosecond time resolved fluorescence spectroscopy. For I
S′, formed by the ...addition of 2 mM sodium dodecyl sulfate (SDS) to the protein, almost total dynamic solvent shift of coumarin 153 (C153) is captured in a picosecond set up and two components of 90 and 400 ps are detected. In another partially unfolded state, I
S″, formed by the addition of 5 M urea to I
S′, only 22% of the total dynamic solvent shift is detected and there are two slow components of 60 and 170 ps. The faster dynamics in I
S″ may be attributed to the expanded and less compact structure of I
S″ compared to I
S′. The slower hydration dynamics in both I
S′ and I
S″, in comparison to bulk water (solvation time
≤
1 ps), is ascribed to the local secondary structure, dynamics of the protein side chain and hindered exchange of bound and free water molecules in cytochrome
C surrounded by SDS and urea.
Persistence length and torsional rigidity for different B-DNA sequences have been calculated by analysing crystal structure database. The values of these parameters for mixed sequence DNA are in good ...agreement with those estimated by others. Persistence lengths for the homopolymeric sequences, namely poly(dA)·poly(dT) and poly(dG)·poly(dC), are significantly large compared to those of others as expected from the inability of these sequences to form nucleosome under normal conditions. The heteropolymeric sequences poly(dA-dC)·poly(dG-dT) and poly(dG-dC)·poly(dG-dC), on the other hand, have smaller persistence lengths. This implies larger flexibility of the d(AC)·d(GT), d(CA)·d(TG), d(GC)·d(GC) and d(CG)·d(CG) doublets, some of which constitute the genetic disease forming triplet repeats d(CTG)·d(CAG) and d(CGG)·d(CCG). Thus it is expected that these triplet repeat sequences are also flexible and wrap around the histone octamer efficiently. Persistence length calculations also indicate larger flexibility for these triplet repeat sequences. Furthermore, our computations reveal that the rigidity of a given DNA sequence is controlled by its ability to form cross-strand bifurcated hydrogen bonds between the successive base pairs. Molecular orbital calculations suggest that these hydrogen bonds are generally extended with bond lengths around 3Å.
In this paper, we present a re-analysis of SuperCDMS data using a profile likelihood approach to search for sub-GeV dark matter particles (DM) through two inelastic scattering channels: ...bremsstrahlung radiation and the Migdal effect. By considering possible inelastic scattering channels, experimental sensitivity can be extended to DM masses that would otherwise be undetectable through the DM-nucleon elastic scattering channel, given the energy threshold of current experiments. We exclude DM masses down to \(220~\textrm{MeV}/c^2\) at \(2.7 \times 10^{-30}~\textrm{cm}^2\) via the bremsstrahlung channel. The Migdal channel search excludes DM masses down to \(30~\textrm{MeV}/c^2\) at \(5.0 \times 10^{-30}~\textrm{cm}^2\).
By using a correlated many body method and using the realistic van der Waals potential we study several statistical measures like the specific heat, transition temperature and the condensate fraction ...of the interacting Bose gas trapped in an anharmonic potential. As the quadratic plus a quartic confinement makes the trap more tight, the transition temperature increases which makes more favourable condition to achieve Bose-Einstein condensation (BEC) experimentally. BEC in 3D isotropic harmonic potential is also critically studied, the correction to the critical temperature due to finite number of atoms and also the correction due to inter-atomic interaction are calculated by the correlated many-body method. Comparison and discussion with the mean-field results are presented.
In this paper, six different grades of Assam CTC black tea liquor were discriminated by means of cyclic voltammetry. A 3-electrode configuration was used to study the voltammogram where ...Polyacrylamide/Exfoliated Graphite composite (PAM/EGC) was used as the working electrode. Data obtained from the tea samples were subjected to multivariate data analysis techniques viz. Radar plot, Box plot and Principal Component Analysis (PCA). The results were found quite promising, thus justifying the suitability of the prepared working electrode for the quality estimation of tea.
