77 research outputs found
Magnetic anisotropy of YbNi4P2
We report on transport and magnetic measurements between 1.8 and 400 K on
single crystalline YbNi4P2, which was recently reported to be a heavy fermion
system with a low lying ferromagnetic transition at T_C=0.17 K, based on data
from polycrystals. The tetragonal crystal structure of YbNi4P2 presents
quasi-one-dimensional Yb chains along the c direction. Here we show that at
high temperatures, the magnetic anisotropy of YbNi4P2 is dominated by the
crystal electrical field effect with an Ising-type behaviour, which gets more
pronounced towards lower temperatures. The electrical resistivity also reflects
the strong anisotropy of the crystal structure and favours transport along c,
the direction of the Yb chains.Comment: SCES 2011 proceedings, in pres
Physical properties and crystal chemistry of Ce2Ga12Pt
Single crystals of the new ternary compound Ce2Ga12Pt were prepared by the
self-flux technique. The crystal structure with the space group P4/nbm was
established from single-crystal X-ray diffraction data and presents a
derivative of the LaGa6Ni0.6 prototype. Magnetic susceptibility measurements
show Curie-Weiss behaviour due to local Ce^3+ moments. At high temperatures,
the magnetic anisotropy is dominated by the crystal-electric-field (CEF) effect
with the easy axis along the crystallographic c direction. Ce2Ga12Pt undergoes
two antiferromagnetic phase transitions at T_N,1 = 7.3K and T_N,2 = 5.5K and
presents several metamagnetic transitions for the magnetic field along c.
Specific-heat measurements prove the bulk nature of these magnetic transitions
and reveal a doublet CEF ground state. The 4f contribution to the resistivity
shows a broad maximum at T_max ~ 85K due to Kondo scattering off the CEF ground
state and excited levels.Comment: 12 pages, accepted in J. Phys.: Condens. Matte
Magnetization study of the energy scales in YbRhSi under chemical pressure
We present a systematic study of the magnetization in YbRhSi
under slightly negative (6?% Ir substitution) and positive (7% Co substitution)
chemical pressure. We show how the critical field , associated with the
high-field Lifshitz transitions, is shifted to lower (higher) values with Co
(Ir) substitution. The critical field , which identifies the
boundary line of the antiferromagnetic (AFM) phase
increases with positive pressure and it approaches zero with 6% Ir
substitution. On the other side, the crossover field , associated with
the energy scale where a reconstruction of the Fermi surface has
been observed, is not much influenced by the chemical substitution.}{Following
the analysis proposed in
Refs.\,\cite{Paschen2004,Gegenwart2007,Friedemann2009,Tokiwa2009a} we have
fitted the quantity with a crossover function to
indentify . The line follows an almost linear -dependence
at sufficiently high fields outside the AFM phase, but it deviates from
linearity at and in
Yb(RhCo)Si it changes slope clearly inside the
AFM phase. Moreover, the FWHM of the fit function depends linearly on
temperature outside the phase, but remains constant inside, suggesting either
that such an analysis is valid only for or that the
Fermi surface changes continuously at inside the AFM phase.}}Comment: 6 pages, 4 figure
Quantum criticality in Yb(Rh0.97Co0.03)2Si2 probed by low-temperature resistivity
Quantum criticality in Yb(Rh0.97Co0.03)2Si2 is investigated by means of
resistivity and magnetoresistance. The partial substitution of Co leads to a
stabilization of the magnetism as expected according to the application of
chemical pressure for Yb systems. However, the signature of the Kondo-breakdown
remains at the same position in the temperature-magnetic field phase diagram
compared to stoichiometric YbRh2Si2. As a consequence, the Kondo-breakdown is
situated within the antiferromagnetic phase. These results fit well within the
global phase diagram under chemical pressure [1].Comment: 4 pages, 4 figures, submitted to ICM/SCES200
Interplay between Co-3d and Ce-4f magnetism in CeCoAsO
We have investigated the ground state properties of polycrystalline CeCoAsO
by means of magnetization, specific heat and solid state NMR. Susceptibility
and specific-heat measurements suggest a ferromagnetic order at about,
=75 K. No further transitions are found down to 2 K. At 6.5 K a
complex Schottky type of anomaly shows up in the specific heat results. The
interplay between Ce-4f and Co-3d magnetism being responsible for that anomaly
is discussed. Furthermore As NMR investigations have been performed to
probe the magnetism on a microscopic scale. As-NMR spectra are analysed in
terms of first and second order quadrupolar interaction. The anisotropic shift
component and could be derived from the
As powder spectra. Towards lower temperature a strong shift anisotropy
was found. Nonetheless tracks the bulk susceptibility down
to 50 K very well. Furthermore the presence of weak correlations among the
Ce ions in the ferromagnetic state is discussed. The observed increase of
towards lower temperatures supports this interpretation.Comment: 6 pages, 4 figures, Accepted in Physical Review
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