1,731 research outputs found
Low temperature magnetic transition in RuSr2EuCeCu2O10 ruthenocuprate
A new magnetic transition in the ruthenocuprate parent compound
RuSr2EuCeCu2O10 has been observed below 10 K. It shows up only as a kink in the
imaginary part of the ac susceptibility and exhibits a pronounced frequency
dependence. At the same time, the real part of the ac susceptibility and the dc
magnetization study show very little change in the same temperature window
suggesting only a minor fraction of the material to be involved in the
transition. Frequency dependence shows excellent agreement with the predictions
of the Arrhenius law known to describe well the dynamics of the
superparamagnetic particles. The same type of the investigation on the
RuSr2Eu1.1Ce0.9Cu2O10 composition showed no evidence of the similar transition,
which points to a possible intrinsic behavior.Comment: to be published in Physica
Two component butterfly hysteresis in Ru1222 ruthenocuprate
We report detailed studies of the ac susceptibility butterfly hysteresis on
the Ru1222 ruthenocuprate compounds. Two separate contributions to these
hysteresis have been identified and studied. One contribution is
ferromagnetic-like and is characterized by the coercive field maximum. Another
contribution, represented by the so called inverted maximum, is related to the
unusual inverted loops, unique feature of Ru1222 butterfly hysteresis. The
different nature of the two identified magnetic contributions is proved by the
different temperature dependences involved. By lowering the temperature the
inverted peak gradually disappears while the coercive field slowly raises. If
the maximum dc field for the hysteresis is increased, the size of the inverted
part of the butterfly hysteresis monotonously grows while the position of the
peak saturates. In reaching saturation exponential field dependence has been
demonstrated to take place. At T = 78 K the saturation field is 42 Oe.Comment: 5 pages, 5 figure
Nonlinear magnetic response in ruthenocuprates
We have performed an investigation of the nonlinear magnetic response in
ruthenocuprates. A negative, diverging-like peak at the main magnetic
transition T_N in RuSr2RECu2O8 (RE = Gd, Y) indicates a possible canted
antiferromagnetic order. Another well defined feature above T_N points to a
blocking of superparamagnetic particles through the T^(-3) dependence of the
third harmonic at higher temperatures. Below T_N a nondiverging peak appears,
which is strongly affected by the addition of 10% of Cu ions in the RuO2
planes. In RuSr2RE(2-x)Ce(x)Cu2O10 the main magnetic transition T_M is
accompanied by two characteristic temperatures in the third harmonic of the ac
susceptibility, in agreement with recent studies from uSR and Mossbauer
spectroscopy. We find that the spin-spin correlation temperature is the same in
both families of ruthenocuprates.Comment: accepted for publication in EPJ
Ni3TeO6 - a collinear antiferromagnet with ferromagnetic honeycomb planes
We report a comprehensive study of magnetic properties of Ni3TeO6. The system
crystallizes in a noncentrosymmetric rhombohedral lattice, space group R3.
There are three differently coordinated Ni atoms in the unit cell. Two of them
form an almost planar honeycomb lattice, while the third one is placed between
the layers. Magnetization and specific heat measurements revealed a single
magnetic ordering at TN = 52 K. Below TN the susceptibility with the magnetic
field parallel to the c-axis drops towards zero while the perpendicular
susceptibility remains constant, a characteristic of antiferromagnetic
materials. Neutron diffraction confirmed that the system is antiferromagnet
below TN with ferromagnetic ab-planes stacked antiferromagnetically along the
c-axis. All Ni moments are in the S = 1 spin state and point along the c-axis.Comment: accepted for publication in Journal of Physics Condensed Matte
Kinetics and mechanism of synthetic CoS oxidation process
The results of investigation of kinetics and mechanism for synthetic a-CoS oxidation process are presented in this paper. Based on experimental data obtained using DTA and XRD analysis and constructed PSD diagrams for Co-S-O system, mechanism of synthetic a-CoS oxidation process is suggested. Characteristic kinetic parameters were obtained for experimental isothermal investigations of desulfurization degree using Sharp method
Isoflavone content and antioxidant properties of soybean seeds
The isoflavone content and antioxidant properties of five Croatian soybean seed cultivars from two locations were analysed. The content of total and individual isofavones was determined by high performance liquid chromatography. For determination of antioxidant properties scavenging capacity on DPPHֹ radicals has been applied. The total phenolic content, oil and protein content in soybean cultivars were also determined. Significant differences in the content of individual isoflavones were observed within the soybean cultivars. The total phenol content in soybean cultivars ranged from 87.2 to 216.3 mg GAE/100g of soybean. The total isoflavone content in soybean seeds ranged from 80.7 to 213.6 mg/100g of soybean. The most abundant isoflavone in soybean seeds was genistein. There was statistically significant difference (p < 0.05) among two locations in total and individual isoflavone contents. The highest contents of total isoflavones were found in cultivar “os55-95”. Conversely, cultivars poor in isoflavones also showed low levels of DPPH-radical scavenging activity
Copper production in Majdanpek in sixties and seventies of the 16th century
In this paper the practice of mine Majdanpek during sixties and seventies of the XVI century has been investigated with an accent on copper production. The attention has been also given to various subjects from considering copper treatment and use to forbidden activities connected to copper illegal production and trade with Persia
Dissipation processes in the insulating skyrmion compound Cu2OSeO3
We present a detailed study of the phase diagram surrounding the skyrmion
lattice (SkL) phase of Cu2OSe2O3 using high-precision magnetic ac
susceptibility measurements. An extensive investigation of transition dynamics
around the SkL phase using the imaginary component of the susceptibility
revealed that at the conical-to-SkL transition a broad dissipation region
exists with a complex frequency dependence. The analysis of the observed
behavior within the SkL phase indicates a distribution of relaxation times
intrinsically related to SkL. At the SkL-to-paramagnet transition a narrow
first-order peak is found that exhibits a strong frequency and magnetic field
dependence. Surprisingly, very similar dependence has been discovered for the
first-order transition below the SkL phase, i.e. where the system enters the
helical and conical state(s), indicating similar processes across the
order-disorder transition.Comment: Accepted for publication in PR
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