712 research outputs found
Green Politics for a Better Earth
Our blue planet provides immeasurable treasures for livelihood, and it is sensible and tolerant. We are degrading our living place for the benefit of material continuance. The material continuance gives us physical pleasures a lot. On the other hand, it creates an eroded future. In this regard, we raise the question of why we are pushing up the blue planet on the line of destruction. We have to take care of the Earth for a better future. For this cause, we have pursued a new paradigm of decision-making instrument as the 'Green Politics' to cope with the material continuance of gatherings. The Green politics question how the tangible exertion for happenings eroded our living places. Once more, it tries to maintain social justice in societies regarding Green political problems. The research paper has gone through reflective research methods
Frequency dependent superfluid stiffness in the pseudogap regime in strongly disordered NbN thin films
We measure the frequency dependence of the complex ac conductivity of NbN
films with different levels of disorder in frequency range 0.4-20 GHz. Films
with low disorder exhibit a narrow dynamic fluctuation regime above T_c as
expected for a conventional superconductor. However, for strongly disordered
samples, the fluctuation regime extends well above T_c, with a strongly
frequency-dependent superfluid stiffness which disappears only at a temperature
T* close to the pseudogap temperature obtained from scanning tunneling
measurements. Such a finite-frequency response is associated to a marked
slowing down of the superconducting fluctuations already below T*. The
corresponding large length-scale fluctuations suggest a scenario of thermal
phase fluctuations between superconducting domains in a strongly disordered
s-wave superconductor.Comment: pdf file: 18 pages including figure
Probing long-range correlations in the Berezinskii-Kosterlitz-Thouless fluctuation regime of ultra-thin NbN superconducting films using transport noise measurements
We probe the presence of long-range correlations in phase fluctuations by
analyzing the higher-order spectrum of resistance fluctuations in ultra-thin
NbN superconducting films. The non-Gaussian component of resistance
fluctuations is found to be sensitive to film thickness close to the
transition, which allows us to distinguish between mean field and
Berezinskii-Kosterlitz-Thouless (BKT) type superconducting transitions. The
extent of non-Gaussianity was found to be bounded by the BKT and mean field
transition temperatures and depend strongly on the roughness and structural
inhomogeneity of the superconducting films. Our experiment outlines a novel
fluctuation-based kinetic probe in detecting the nature of superconductivity in
disordered low-dimensional materials.Comment: submitted to PR
Self organized criticality of magnetic avalanches in disordered ferrimagnetic material
We observe multiple step-like jumps in a Dy-Fe-Ga-based ferrimagnetic alloy
in its magnetic hysteresis curve at 2 K. The observed jumps have a stochastic
character with respect to their magnitude and the critical field of occurrence,
and the jumps do not show any temporal effect. The jump size distribution
follows a power law variation indicating the scale invariance nature of the
jumps. We have invoked a simple two-dimensional random bond Ising-type spin
system to model the dynamics. Our computational work can qualitatively
reproduce the jumps and their scale invariant character. It also elucidates
that the flipping of antiferromagnetically coupled Dy and Fe clusters is
responsible for the observed discrete avalanche-like features in the hysteresis
loop. These characteristics indicate that the present phenomenon can be well
described within the realm of self-organized criticalityComment: 12 pages, 13 figure
Non-linear characteristics in two-dimensional superconductors: Berezinskii-Kosterlitz-Thouless physics vs inhomogeneity
One of the hallmarks of the Berezinskii-Kosterlitz-Thouless (BKT) transition
in two-dimensional (2D) superconductors is the universal jump of the superfluid
density, that can be indirectly probed via the non-linear exponent of the
current-voltage characteristics. Here, we compare the experimental
measurements of characteristics in two cases, namely NbN thin films and
SrTiO-based interfaces. While the former display a paradigmatic example of
BKT-like non-linear effects, the latter do not seem to justify a BKT analysis.
Rather, the observed characteristics can be well reproduced theoretically
by modelling the effect of mesoscopic inhomogeneity of the superconducting
state. Our results offer an alternative perspective on the spontaneous
fragmentation of the superconducting background in confined 2D systems.Comment: Final version, as publishe
Centrosymmetric-noncentrosymmetric Structural Phase Transition in Quasi one-dimensional compound, (TaSe)I
(TaSe)I, a compound belonging to the family of quasi-one-dimensional
transition-metal tetrachalcogenides, has drawn significant attention due to a
recent report on possible coexistence of two antagonistic phenomena,
superconductivity and magnetism below 2.5~K (Bera et. al, arXiv:2111.14525).
Here, we report a structural phase transition of the trimerized phase at
temperature, ~145~K using Raman scattering, specific heat, and
electrical transport measurements. The temperature-dependent single-crystal
X-ray diffraction experiments establish the phase transition from a
high-temperature centrosymmetric to a low-temperature non-centrosymmetric
structure, belonging to the same tetragonal crystal family. The first-principle
calculation finds the aforementioned inversion symmetry-breaking structural
transition to be driven by the hybridization energy gain due to the off-centric
movement of the Ta atoms, which wins over the elastic energy loss.Comment: 11 pages, 5 figures, Under review as a regular articl
High transport spin polarization in the van der Waals ferromagnet FeGeTe
The challenging task of scaling-down the size of the power saving electronic
devices can be accomplished by exploiting the spin degree of freedom of the
conduction electrons in van der Waals (vdW) spintronic architectures built with
2D materials. One of the key components of such a device is a near-room
temperature 2D ferromagnet with good metallicity that can generate a highly
spin-polarized electronic transport current. However, most of the known 2D
ferromagnets have either a very low temperature ordering, poor conductivity, or
low spin polarization. In this context, the FeGeTe (with )
family of ferromagnets stand out due to their near-room temperature
ferromagnetism and good metallicity. We have performed spin-resolved Andreev
reflection spectroscopy on FeGeTe ( 273 K) and
demonstrated that the ferromagnet is capable of generating a very high
transport spin polarization, exceeding 50. This makes FeGeTe a
strong candidate for application in all-vdW power-saving spintronic devices.Comment: Accepted for publication in Physical Review
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