782 research outputs found
Synthesis and physico-chemical studies of some Bisphenol Derrivatives, Polymers and Composites
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Thermal Expansion and Magnetostriction Studies of a Kondo Lattice Compound: Ceagsb2
We have investigated a single crystal of CeAgSb2 using low field
ac-susceptibility, thermal expansion and magnetostriction measurements in the
temperature range 1.5K to 90K. The ac-susceptibility exhibits a sharp peak at
9.7K for both B//c and B perp c due to the magnetic ordering of the Ce moment.
The thermal expansion coefficient alpha, exhibits highly anisotropic behaviour
between 3K and 80K : alpha is positive for dL/L perp c, but negative for dL/L
// c. Furthermore, alpha (for dL/L) perp c (i.e. in ab-plane) exhibits a sharp
peak at TN followed by a broad maximum at 20K, while a sharp negative peak at
TN followed by a minimum at 20K has been observed for (dL/L //) the c
direction. The observed maximum and minimum in alpha(T) at 20K have been
attributed to the crystalline field effect on the J=5/2 state of the Ce3+ ion.
The magnetostriction also exhibits anisotropic behaviour with a large
magnetostriction along the c-axis. The ab-plane magnetostriction exhibits a
peak at B=3.3T at 3K, which is consistent with the observed peak in the
magnetoresistance measurements.Comment: 4 Pages (B5), 3 figures, submitted to SCES200
On an extension of Nori and local fundamental group schemes
This article studies an extended Nori and local fundamental group schemes of
Abelian varieties. We also discuss the birational invariance of these group
schemes and study their behaviour under the Albanese and \'{e}tale morphisms.Comment: Added some new results related to the local fundamental group scheme,
a new section on extended local fundamental group scheme; accordingly, the
title is change
Magnetic and transport properties of Pr2Pt3Si5
We have investigated the magnetic and transport properties of a
polycrystalline Pr2Pt3Si5 sample through the dc and ac magnetic
susceptibilities, electrical resistivity, and specific heat measurements. The
Rietveld refinement of the powder X-ray diffraction data reveals that Pr2Pt3Si5
crystallizes in the U2Co3Si5-type orthorhombic structure (space group Ibam).
Both the dc and ac magnetic susceptibility data measured at low fields exhibit
sharp anomaly near 15 K. In contrast, the specific heat data exhibit only a
broad anomaly implying no long range magnetic order down to 2 K. The broad
Schottky-type anomaly in low temperature specific heat data is interpreted in
terms of crystal electric field (CEF) effect, and a CEF-split singlet ground
state is inferred. The absence of the long range order is attributed to the
presence of nonmagnetic singlet ground state of the Pr3+ ion. The electrical
resistivity data exhibit metallic behavior and are well described by the
Bloch-Gr\"uniesen-Mott relation.Comment: 6 pages, 8 figure
Unconventional superconductivity in the cage type compound ScRhSn
We have examined the superconducting ground state properties of the caged
type compound ScRhSn using magnetization, heat capacity, and
muon-spin relaxation or rotation (SR) measurements. Magnetization
measurements indicate type-II superconductivity with an upper critical field
= 7.24 T. The zero-field cooled and field cooled
susceptibility measurements unveil an onset of diamagnetic signal below = 4.4 K. The interpretation of the heat capacity results below
using the BCS model unveils the value of = 2.65, which gives
the dimensionless ratio 2 = 5.3, intimating that
ScRhSn is a strong-coupling BCS superconductor. The zero-field
SR measurements in the longitudinal geometry exhibit a signature of a
spontaneous appearance of the internal magnetic field below the superconducting
transition temperature, indicating that the superconducting state is
characterized by the broken time-reversal symmetry (TRS). We have compared the
results of broken TRS in ScRhSn with that observed in
RRhSn (R = Lu and Y).Comment: 6 pages, 4 figures. arXiv admin note: text overlap with
arXiv:1411.687
Commensurate to incommensurate magnetic phase transition in Honeycomb-lattice pyrovanadate Mn2V2O7
We have synthesized single crystalline sample of MnVO using
floating zone technique and investigated the ground state using magnetic
susceptibility, heat capacity and neutron diffraction. Our magnetic
susceptibility and heat capacity reveal two successive magnetic transitions at
19 K and 11.8 K indicating two distinct magnetically
ordered phases. The single crystal neutron diffraction study shows that in the
temperature () range 11.8 K 19 K the magnetic structure is
commensurate with propagation vector , while upon lowering
temperature below 11.8 K an incommensurate magnetic order emerges
with and the magnetic structure can be represented by
cycloidal modulation of the Mn spin in plane. We are reporting this
commensurate to incommensurate transition for the first time. We discuss the
role of the magnetic exchange interactions and spin-orbital coupling on the
stability of the observed magnetic phase transitions.Comment: 8 pages, 7 figure
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