20 research outputs found
Magnetic Behavior of Single Crystalline Pr_{5}Ge_{3} and Tb_{5}Ge_{3}Compounds
The results of the magnetization studies on Pr_{5}Ge_{3}and Tb_{5}Ge_{3}
single crystals are reported. Single Crystals of Pr_{5}Ge_{3} and Tb_{5}Ge_{3}
compounds were successfully grown by Czochralski method. These compounds
crystallize in a Mn_{5}Si_{3} type hexagonal structure with space group
P6_{3}/mcm. Ferromagnetic correlations set in at around 36 K in Pr_{5}Ge_{3} in
the ab plane followed by an antiferromagnetic transition at 13 K. Along the
c-axis the magnetization shows a ferromagnetic transition around 13 K with an
overall ferrimagnetic behavior. At 2K, the magnetic isotherm of the compound
along [0001] direction is typical for a ferromagnet, while a field induced
ferromagnetic type response is observed along the [10\overline{\mathit{1}}0]
direction. Hexagonal ab plane or [10\overline{\mathit{1}}0] direction was found
to be the easy axis of magnetization. Tb_{5}Ge_{3} orders antiferromagneticaly
at 85 K with the hexagonal ab plane as easy axis of magnetization. The compound
shows a field induced ferromagnetic behavior in its magnetic isotherm at 2 K.Comment: In Communication with a Journa
Thermal and Transport Behavior of Single Crystalline R2CoGa8 (R = Gd, Tb, Dy, Ho, Er, Tm, Lu and Y) Compounds
The anisotropy in electrical transport and thermal behavior of single
crystalline RCoGa series of compounds is presented. These compounds
crystallize in a tetragonal structure with space gropup P4/mmm. The nonmagnetic
counterparts of the series namely YCoGa and LuCoGashow
a behavior consistent with the low density of states at the fermi level. In
YCoGa, a possibility of charge density wave transition is observed
at 30 K. GdCoGa and ErCoGa show a presence of
short range correlation above the magnetic ordering temperature of the
compound. In case of GdCoGa, the magnetoresistance exhibits a
significant anisotropy for current parallel to {[}100{]} and {[}001{]}
directions. Compounds with other magnetic rare earths (R = Tb, Dy, Ho and Tm)
show the normal expected magnetic behavior whereas DyCoGa exhibits
the possibility of charge density wave (CDW) transition at approximately same
temperature as that of YCoGa. The thermal property of these
compounds is analysed on the basis of crystalline electric field (CEF)
calculations.Comment: 10 Pages 14 Figures. Submitted to PR
Temperature dependence of transport spin polarization in NdNi5 measured using Point Contact Andreev reflection
We report a study in which Point contact Andreev reflection (PCAR)
spectroscopy using superconducting Nb tip has been carried out on NdNi5, a
ferromagnet with a Curie temperature of TC~7.7K. The measurements were carried
out over a temperature range of 2-9K which spans across the ferromagnetic
transition temperature. From an analysis of the spectra, we show that (i) the
temperature dependence of the extracted value of transport spin polarization
closely follows the temperature dependence of the spontaneous magnetization;
(ii) the superconducting quasiparticle lifetime shows a large decrease close to
the Curie temperature of the ferromagnet. We attribute the latter to the
presence of strong ferromagnetic spin fluctuations in the ferromagnet close to
the ferromagnetic transition temperature.Comment: pdf file including figures-Typographical error and errors in
references correcte
Magnetic and Transport Properties of Ternary Indides of type R2CoIn8 (R = Ce, Pr and Dy)
We have synthesized and investigated the magnetic and transport properties of
a series of compounds, R2CoIn8 (R = rare earth). Compounds form in single phase
with a tetragonal structure (space group P4/mmm, no. 162). The Ce compound
shows heavy fermion behavior. The magnetic susceptibility of Pr2CoIn8 shows a
marked deviation from the Curie-Weiss behavior at low temperatures, which is
attributed to the crystalline electric field effects. Heat capacity and
magnetization measurements show that Dy2CoIn8 undergoes a magnetic transition
at 17 K and a second transition near 5 K, the latter of which may be due to
spin reorientation. Magnetization of this compound shows two metamagnetic
transitions approximately at 3.6 T and 8.3 T.Comment: Total 7 pages of text and figure
Magnetic Anisotropy in Single Crystalline CeAuIn
We have grown the single crystals of LaAuIn and
CeAuIn by high temperature solution method and report on the
anisotropic magnetic behavior of CeAuIn . The compounds crystallize
in an orthorhombic structure with space group \textit {Pnma}.
LaAuIn shows a Pauli-paramagnetic behavior. CeAuIn do
not order down to 1.8 K. The easy axis of magnetization for CeAuIn
is along [010] direction. The magnetization data is analyzed on the basis of
crystalline electric field (CEF) model.Comment: 7 figures 4 page
Magnetic Behavior in RRhX (R = rare earths; X=B, C) Compounds
We report on the magnetic behavior of RRhB (R = La, Ce, Pr, Nd, Gd, Tb and
Tm) and RRhC (R = La, Ce, Pr and Gd) compounds crystallizing in the cubic
perovskite type structure with space group Pm3m. The heat capacity data on
Pauli-paramagnetic LaRhB and LaRhC indicate a high frequency vibrating motion
of boron and carbon atoms in the unit cell. Ce is in -like nonmagnetic state in
both the compounds. Pr compounds show a dominant crystal field effect with a
nonmagnetic singlet ground state in PrRhB and a nonmagnetic quadrupolar doublet
in PrRhC. Compounds with other rare earths order ferromagnetically at low
temperatures except TmRhB in which the zero field evolution of magnetic
interactions is relatively more complicated. The electrical resistivity of
GdRhB decreases with increasing temperature in the paramagnetic state in the
vicinity of T, which is rarely seen in ferromagnets. The behavior is discussed
to be arising due to the short range spin fluctuation and a possible
contribution from Fermi surface geometry.Comment: 14 Figs and a text fil
Crystal Growth and Anisotropic Magnetic Properties of RAgGe (R = Pr, Nd and Sm) Single Crystals
We report the single crystal growth and anisotropic magnetic properties of
the tetragonal RAgGe (R = Pr, Nd and Sm) compounds which crystallize in
the ThCrSi type crystal structure with the space group \textit{I4/mmm}.
The single crystals of RAgGe (R = Pr, Nd and Sm) were grown by
self-flux method using Ag:Ge binary alloy as flux. From the magnetic studies on
single crystalline samples we have found that PrAgGe and NdAgGe
order antiferromagnetically at 12 K and 2 K respectively, thus corroborating
the earlier polycrystalline results. SmAgGe also orders
antiferromagnetically at 9.2 K. The magnetic susceptibility and magnetization
show a large anisotropy and the easy axis of magnetization for PrAgGe
and NdAgGe is along the [100] direction where as it changes to [001]
direction for SmAgGe. Two metamagnetic transitions were observed in
NdAgGe at = 1.25 T and =3.56 T for the field
parallel to [100] direction where as the magnetization along [001] direction
was linear indicating the hard axis of magnetization.Comment: 4 pages, 4 figures, submitted to SCES-2008 Proceedings. Submitted to
SCES - 2008 Proceeding
Magnetic properties of single-crystalline CeCuGa3
The magnetic behavior of single-crystalline CeCuGa3 has been investigated.
The compound forms in a tetragonal BaAl4-type structure consisting of
rare-earth planes separated by Cu-Ga layers. If the Cu-Ga site disorder is
reduced, CeCuGa3 adopts the related, likewise tetragonal BaNiSn3-type
structure, in which the Ce ion are surrounded by different Cu and Ga layers and
the inversion symmetry is lost. In the literature conflicting reports about the
magnetic order of CeCuGa3 have been published. Single crystals with the
centrosymmetric structure variant exhibit ferromagnetic order below approx. 4 K
with a strong planar anisotropy. The magnetic behavior above the transition
temperature can be well understood by the crystal-field splitting of the 4f
Hund's rule ground-state multiplet of the Ce ions
Magnetocrystalline anisotropy in RAu_{2}Ge_{2} (R = La, Ce and Pr) single crystals
Anisotropic magnetic properties of single crystalline RAu_{2}Ge_{2} (R = La,
Ce and Pr) compounds are reported. LaAu_{2}Ge_{2} exhibit a Pauli-paramagnetic
behavior whereas CeAu_{2}Ge_{2} and PrAu_{2}Ge_{2} show an antiferromagnetic
ordering with N\grave{e}el temperatures T_{N} = 13.5 and 9 K, respectively. The
anisotropic magnetic response of Ce and Pr compounds establishes [001] as the
easy axis of magnetization and a sharp spin-flip type metamagnetic transition
is observed in the magnetic isotherms. The resistance and magnetoresistance
behavior of these compounds, in particular LaAu_{2}Ge_{2}, indicate an
anisotropic Fermi surface. The magnetoresistivity of CeAu_{2}Ge_{2} apparently
reveals the presence of a residual Kondo interaction. A crystal electric field
analysis of the anisotropic susceptibility in conjunction with the
experimentally inferred Schottky heat capacity enables us to propose a crystal
electric field level scheme for Ce and Pr compounds. For CeAu_{2}Ge_{2} our
values are in excellent agreement with the previous reports on neutron
diffraction. The heat capacity data in LaAu_{2}Ge_{2} show clearly the
existence of Einstein contribution to the heat capacity.Comment: Submitted to PRB 11 Pages 13 Figure