258 research outputs found
Marketing Efficiency of Dairy Products for Co-operative and Private Dairy Plants in Tamil Nadu - A Comparative Analysis
The marketing of milk and milk products by dairy plants of co-operative and private sectors in Tamil Nadu has been compared. The study is based on the data collected for toned milk, standardized milk, full cream milk, flavoured milk, butter and ghee from the selected co-operative and private dairy plants of the Coimbatore district for the financial year 2001-2002. It has been found that the marketing cost for toned milk is same in both the dairy plants , whereas it is higher for standardized milk, full cream milk and flavoured milk in the co-operative dairy plant. The marketing cost has been found less in the cooperative plant for products like butter and ghee . All the dairy products earn more marketing margins in the private than co-operative dairy plant, except for toned milk .The marketing efficiency of cooperative dairy plant for all dairy products has been observed relatively less than that of private dairy plant, except toned milk .The study has suggested the development of co-operative dairy industry in a sustainable manner, the co-operative dairy plants should formulate long-term vision and strategy. The study has observed that value addition in dairy products should be done without compromising the quality and consumer-oriented market research and development should be accorded greater attention .Marketing,
Physical Properties of Metallic Antiferromagnetic CaCo{1.86}As2 Single Crystals
We report studies of CaCo{1.86}As2 single crystals. The electronic structure
is probed by angle-resolved photoemission spectroscopy (ARPES) measurements of
CaCo{1.86}As2 and by full-potential linearized augmented-plane-wave
calculations for the supercell Ca8Co15As16 (CaCo{1.88}As2). Our XRD crystal
structure refinement is consistent with the previous combined refinement of
x-ray and neutron powder diffraction data showing a collapsed-tetragonal
ThCr2Si2-type structure with 7(1)% vacancies on the Co sites corresponding to
the composition CaCo{1.86}As2 [D. G. Quirinale et al., Phys. Rev. B 88, 174420
(2013)]. The anisotropic magnetic susceptibility chi(T) data are consistent
with the magnetic neutron diffraction data of Quirianale et al. that
demonstrate the presence of A-type collinear antiferromagnetic order below the
Neel temperature TN = 52(1) K with the easy axis being the tetragonal c axis.
However, no clear evidence from the resistivity rho(T) and heat capacity Cp(T)
data for a magnetic transition at TN is observed. A metallic ground state is
demonstrated from band calculations and the rho(T), Cp(T) and ARPES data, and
spin-polarized calculations indicate a competition between the A-type AFM and
FM ground states. The Cp(T) data exhibit a large Sommerfield electronic
coefficient reflecting a large density of states at the Fermi energy D(EF),
consistent with the band structure calculations which also indicate a large
D(EF) arising from Co 3d bands. At 1.8 K the M(H) data for H|| c exhibit a
well-defined first-order spin-flop transition at an applied field of 3.5 T. The
small ordered moment of 0.3 muB/Co obtained from the M(H) data at low T, the
large exchange enhancement of chi and the lack of a self-consistent
interpretation of the chi(T) and M(H,T) data in terms of a local moment
Heisenberg model together indicate that the magnetism of CaCo{1.86}As2 is
itinerant.Comment: 18 pages, 15 figures, 4 tables, 61 references; v2: extended the fits
of experimental data by additional electronic structure calculations;
published versio
Experimental and theoretical electronic structure of EuRh2As2
The Fermi surfaces (FS's) and band dispersions of EuRh2As2 have been
investigated using angle-resolved photoemission spectroscopy. The results in
the high-temperature paramagnetic state are in good agreement with the full
potential linearized augmented plane wave calculations, especially in the
context of the shape of the two-dimensional FS's and band dispersion around the
Gamma (0,0) and X (pi,pi) points. Interesting changes in band folding are
predicted by the theoretical calculations below the magnetic transition
temperature Tn=47K. However, by comparing the FS's measured at 60K and 40K, we
did not observe any signature of this transition at the Fermi energy indicating
a very weak coupling of the electrons to the ordered magnetic moments or strong
fluctuations. Furthermore, the FS does not change across the temperature (~
25K) where changes are observed in the Hall coefficient. Notably, the Fermi
surface deviates drastically from the usual FS of the superconducting
iron-based AFe2As2 parent compounds, including the absence of nesting between
the Gamma and X FS pockets.Comment: 4 pages, 4 figure
Dramatic Changes in the Electronic Structure Upon Transition to the Collapsed Tetragonal Phase in CaFe2As2
We use angle-resolved photoemission spectroscopy (ARPES) and density
functional theory (DFT) calculations to study the electronic structure of
CaFeAs in previously unexplored collapsed tetragonal (CT) phase. This
unusual phase of the iron arsenic high temperature superconductors was hard to
measure as it exists only under pressure. By inducing internal strain, via the
post growth, thermal treatment of the single crystals, we were able to
stabilize the CT phase at ambient-pressure. We find significant differences in
the Fermi surface topology and band dispersion data from the more common
orthorhombic-antiferromagnetic or tetragonal-paramagnetic phases, consistent
with electronic structure calculations. The top of the hole bands sinks below
the Fermi level, which destroys the nesting present in parent phases. The
absence of nesting in this phase along with apparent loss of Fe magnetic
moment, are now clearly experimentally correlated with the lack of
superconductivity in this phase.Comment: 5 pages, 4 figures, accepted in PRB(RC
Unusual temperature dependence of band dispersion in Ba(Fe(1-x)Ru(x))2As2 and its consequences for antiferromagnetic ordering
We have performed detailed studies of the temperature evolution of the
electronic structure in Ba(Fe(1-x)Ru(x))2As2 using Angle Resolved Photoemission
Spectroscopy (ARPES). Surprisingly, we find that the binding energy of both
hole and electron bands changes significantly with temperature in pure and Ru
substituted samples. The hole and electron pockets are well nested at low
temperature in unsubstituted (BaFe2As2) samples, which likely drives the spin
density wave (SDW) and resulting antiferromagnetic order. Upon warming, this
nesting is degraded as the hole pocket shrinks and the electron pocket expands.
Our results demonstrate that the temperature dependent nesting may play an
important role in driving the antiferromagnetic/paramagnetic phase transition.Comment: 5 pages, 6 figure
Exotic Kondo crossover in a wide temperature region in the topological Kondo insulator SmB6 revealed by high-resolution ARPES
Temperature dependence of the electronic structure of SmB6 is studied by
high-resolution ARPES down to 1 K. We demonstrate that there is no essential
difference for the dispersions of the surface states below and above the
resistivity saturating anomaly (~ 3.5 K). Quantitative analyses of the surface
states indicate that the quasi-particle scattering rate increases linearly as a
function of temperature and binding energy, which differs from Fermi-Liquid
behavior. Most intriguingly, we observe that the hybridization between the d
and f states builds gradually over a wide temperature region (30 K < T < 110
K). The surface states appear when the hybridization starts to develop. Our
detailed temperature-dependence results give a complete interpretation of the
exotic resistivity result of SmB6, as well as the discrepancies among
experimental results concerning the temperature regions in which the
topological surface states emerge and the Kondo gap opens, and give new
insights into the exotic Kondo crossover and its relationship with the
topological surface states in the topological Kondo insulator SmB6.Comment: 8 pages, 5 figure
Probing the electronic and local structure of SrLaCoNbO using near-edge and extended x-ray absorption fine structures
We report the electronic and local structural investigation of double
pervoskites SrLaCoNbO ( 0--1) using x-ray absorption near
edge structure (XANES) and extended x-ray absorption fine structures (EXAFS) at
the Nb, Co, and Sr -edges. The simulations and detailed
analysis of the Nb and Co -edge XANES spectra demonstrate that the observed
pre-edge features arise from the transition of 1 electrons to the mixed
hybridized states. We reveal a -out Jahn-Teller (JT) distortion in the
CoO octahedra, which decreases monotonically due to an enhancement in the
JT inactive Co ions with . On the other hand, the -in distortion
in NbO octahedra remains unaltered up to 0.4 and then decreases with
further increase in . This sudden change in the local coordination around Nb
atoms is found to be responsible for the evolution of the antiferromagnetic
interactions in 0.6 samples. Also, we establish a correlation
between the degree of octahedral distortion and intensity of the white line
feature in the XANES spectra and possible reason for this are discussed. More
interestingly, we observe the signature of KN double electron excitation in
the Sr -edge EXAFS spectra for all the samples, which is found to be in good
agreement with the +1 approximation. Further, the Co L edge shows
the reduction in the crystal field strength and hence an increase in the charge
transfer energy () with the La substitution.Comment: submitte
Direct observation of the spin texture in strongly correlated SmB6 as evidence of the topological Kondo insulator
The concept of a topological Kondo insulator (TKI) has been brought forward
as a new class of topological insulators in which non-trivial surface states
reside in the bulk Kondo band gap at low temperature due to the strong
spin-orbit coupling [1-3]. In contrast to other three-dimensional (3D)
topological insulators (e.g. Bi2Se3), a TKI is truly insulating in the bulk
[4]. Furthermore, strong electron correlations are present in the system, which
may interact with the novel topological phase. Applying spin- and
angle-resolved photoemission spectroscopy (SARPES) to the Kondo insulator SmB6,
a promising TKI candidate, we reveal that the surface states of SmB6 are spin
polarized, and the spin is locked to the crystal momentum. Counter-propagating
states (i.e. at k and -k) have opposite spin polarizations protected by
time-reversal symmetry. Together with the odd number of Fermi surfaces of
surface states between the 4 time-reversal invariant momenta in the surface
Brillouin zone [5], these findings prove, for the first time, that SmB6 can
host non-trivial topological surface states in a full insulating gap in the
bulk stemming from the Kondo effect. Hence our experimental results establish
that SmB6 is the first realization of a 3D TKI. It can also serve as an ideal
platform for the systematic study of the interplay between novel topological
quantum states with emergent effects and competing order induced by strongly
correlated electrons.Comment: 4 figure
Ba{1-x}KxMn2As2: An Antiferromagnetic Local-Moment Metal
The compound BaMn2As2 with the tetragonal ThCr2Si2 structure is a
local-moment antiferromagnetic insulator with a Neel temperature TN = 625 K and
a large ordered moment mu = 3.9 mu_B/Mn. We demonstrate that this compound can
be driven metallic by partial substitution of Ba by K, while retaining the same
crystal and antiferromagnetic structures together with nearly the same high TN
and large mu. Ba_{1-x}K_xMn2As2 is thus the first metallic ThCr2Si2-type
MAs-based system containing local 3d transition metal M magnetic moments, with
consequences for the ongoing debate about the local moment versus itinerant
pictures of the FeAs-based superconductors and parent compounds. The
Ba_{1-x}K_xMn2As2 class of compounds also forms a bridge between the layered
iron pnictides and cuprates and may be useful to test theories of high Tc
superconductivity.Comment: 5 two-column typeset pages, 5 figures, 20 references; v2: minor
revisions, 4 new references, published versio
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