129 research outputs found
Samarium Magnetism Studied on SmPd2Al3 Single Crystal
In this paper, specific features of Sm magnetism in an intermetallic compound
have been studied. For this purpose, a high-quality single crystal of SmPd2Al3
was grown and subjected to detailed measurements of specific heat,
magnetization, ac susceptibility, and electrical resistivity with respect to
temperature and a magnetic field applied along the principal crystallographic
directions. SmPd2Al3 magnetism was found to be strongly anisotropic with the
easy-magnetization direction along the c axis where the main magnetic features
are concentrated. The a-axis response remains weak, paramagneticlike, even in
the magnetically ordered state. Ferromagnetism with TC=12.4 K has been
indicated by all the measured physical properties. At lower temperatures, three
successive order-order phase transitions have been observed on the temperature
dependence of the specific heat as three anomalies: at 3.4, 3.9, and 4.4 K,
respectively. The low-temperature magnetization data can be understood within a
scenario that considers the antiferromagnetic ground state as being gradually
destroyed through a series of four metamagnetic transitions at 0.03, 0.35, 0.5,
and 0.75 T, as detected in the 1.8 K magnetization data. The experimental data
are discussed together with the results of electronic-structure and
crystal-field calculations from first principles, which were performed as an
important part of the study for comprehension and explanation of the observed
behavior of the SmPd2Al3 compound
Pressure Evolution of Magnetism in URhGa
In this paper, we report the results of an ambient and high pressure study of
a 5f-electron ferromagnet URhGa. The work is focused on measurements of
magnetic and thermodynamic properties of a single crystal sample and on the
construction of the p-T phase diagram. Diamond anvil cells were employed to
measure the magnetization and electrical resistivity pressures up to ~ 9 GPa.
At ambient pressure, URhGa exhibits collinear ferromagnetic ordering of uranium
magnetic moments {\mu}U ~ 1.1 {\mu}B (at 2 K) aligned along the c-axis of the
hexagonal crystal structure below the Curie temperature TC = 41K. With the
application of pressure up to 5GPa the ordering temperature TC initially
increases whereas the saturated moment slightly decreases. The rather
unexpected evolution is put in the context of the UTX family of compounds.Comment: arXiv admin note: text overlap with arXiv:1611.0327
Colloquium: Hidden Order, Superconductivity, and Magnetism -- The Unsolved Case of URu2Si2
This Colloquium reviews the 25 year quest for understanding the continuous
(second-order) mean-field-like phase transition occurring at 17.5 K in URu2Si2.
About ten years ago, the term hidden order (HO) was coined and has since been
utilized to describe the unknown ordered state, whose origin cannot be
disclosed by conventional solid-state probes, such as x rays, neutrons, or
muons. HO is able to support superconductivity at lower temperatures (Tc ~ 1.5
K), and when magnetism is developed with increasing pressure both the HO and
the superconductivity are destroyed. Other ways of probing the HO are via
Rh-doping and very large magnetic fields. During the last few years a variety
of advanced techniques have been tested to probe the HO state and their
attempts will be summarized. A digest of recent theoretical developments is
also included. It is the objective of this Colloquium to shed additional light
on the HO state and its associated phases in other materials.Comment: 25 pages, 16 figures, published in Reviews of Modern Physic
Physics of Polymorphic Transitions in CeRuSn
We report a detailed study of the polymorphic transitions in ternary stannide
CeRuSn on high quality single crystals through a combination of X-ray
diffraction experiments conducted at 300, 275 and 120 K, and measurements of
the thermal expansion, magnetization, and resistivity, along main
crystallographic axes. In addition, the transition was followed as a function
of pressure up to 0.8 GPa. The present X-ray diffraction data show that the
room temperature polymorph consists of the lattice doubled along the c axis
with respect to the CeCoAl-type structure consistent with previous reports.
Upon cooling, the compound undergoes two successive transitions, first to a
quintuple (290 K) and than to a triple CeCoAl superstructure at 225 K. The
transitions are accompanied by a tremendous volume change due to a strong
shrinking of the lattice along the c axis, which is clearly observed in thermal
expansion. We advance arguments that the volume collapse originates from an
increasing number of crystallographically inequivalent Ce sites and the change
of ratio between the short and long Ce-Ru bonds. The observed properties of the
polymorphic transition in CeRuSn are reminiscent of the transition in
elementary Cerium, suggesting that similar physics, i.e., a Kondo influenced
transition and strong lattice vibrations might be the driving forces
- …