548 research outputs found
Quantum Magnetic Properties in Perovskite with Anderson Localized Artificial Spin-1/2
Quantum magnetic properties in a geometrically frustrated lattice of spin-1/2
magnet, such as quantum spin liquid or solid and the associated spin
fractionalization, are considered key in developing a new phase of matter. The
feasibility of observing the quantum magnetic properties, usually found in
geometrically frustrated lattice of spin-1/2 magnet, in a perovskite material
with controlled disorder is demonstrated. It is found that the controlled
chemical disorder, due to the chemical substitution of Ru ions by Co-ions, in a
simple perovskite CaRuO3 creates a random prototype configuration of artificial
spin-1/2 that forms dimer pairs between the nearest and further away ions. The
localization of the Co impurity in the Ru matrix is analyzed using the Anderson
localization formulation. The dimers of artificial spin-1/2, due to the
localization of Co impurities, exhibit singlet-to-triplet excitation at low
temperature without any ordered spin correlation. The localized gapped
excitation evolves into a gapless quasi-continuum as dimer pairs break and
create freely fluctuating fractionalized spins at high temperature. Together,
these properties hint at a new quantum magnetic state with strong resemblance
to the resonance valence bond system.Comment: 8 pages, 6 figure
Spectroscopic observations of novae V1065 CEN and V1280 SCO using 45 cm cassegrain telescope at Arthur C Clarke Institute
The spectroscopic observations of two novae namely V1065 CEN and V1280 SCO
were made by 45 cm Cassegrain telescope in high resolution
(=22000) at H (6563 \r{A}) region. V1065 CEN is
He/N-type spectra which characterize a broad (Gaussian FWHM 49 \r{A}), saddle
shaped and asymmetric H emission line without prominent P-Cyg
absorption component. Completely different H profile of V1280 SCO shows
prominent P-Cyg absorption and narrow emission line (Gaussian FWHM 26 \r{A})
which can be classified as Fe II type nova. The expansion velocities of these
two systems measured from the minima of the P-Cyg profiles are close to 2300
km/s for V1065 CEN, and 716 km/s for V1280 SCO. Based on the photometric
analysis, the Nova V1065 CEN can be classified as fast (11t25)
nova. The derived absolute magnitudes at maximum for nova V1065 CEN to be
M = -7.580.18 and M= -7.750.25 correspond to a
distance 8.510.33 kpc. The parameters t=12 days and t=14
days of nova V1280 SCO determine that the nova is in between very fast and fast
nova. The mean absolute magnitude at maximum is calculated to be
M=-8.70.1 and the estimated distance to the nova V1280 SCO is
3.20.2 kpc
Quantum magnetic properties and metal-to-insulator transition in chemically doped calcium ruthenate perovskite
Ruthenates provide comprehensive platform to study a plethora of novel
properties, such as quantum magnetism, superconductivity and magnetic
fluctuation mediated metal-insulator transition. In this article, we provide an
overview of quantum mechanical phenomenology in calcium ruthenium oxide with
varying compositions. While the stochiometric composition of CaRuO
exhibits non-Fermi liquid behavior with quasi-criticality, chemically doped
compounds depict prominent signatures of quantum magnetic fluctuations at low
temperature that in some cases are argued to mediate in metal-insulator
transition. In the case of cobalt doped- CaRuO, an unusual continuum
fluctuation is found to persist deep inside the glassy phase of the material.
These observations reflect the richness of ruthenate research platform in the
study of quantum magnetic phenomena of fundamental importance.Comment: 7 pages, 8 figure
Proteins in Ionic Liquids: Reactions, Applications and Futures
Biopolymer processing and handling is greatly facilitated by the use of ionic liquids, given the increased solubility, and in somecases, structural stability imparted to these molecules. Focussing on proteins, we highlight here not just the key drivers behind protein-ionic liquid interactions that facilitate these functionalities, but address relevant current and potential applications of protein-ionic liquid interactions, including areas of future interest
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