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

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

Pressure-induced huge increase of Curie temperature of the van der Waals ferromagnet VI3

Evolution of magnetism in single crystals of the van der Waals compound VI3 in external pressure up to 7.3 GPa studied by measuring magnetization and ac magnetic susceptibility is reported. Four magnetic phase transitions, at T1 = 54.5 K, T2 = 53 K, TC = 49.5 K, and TFM = 26 K, respectively have been observed at ambient pressure. The first two have been attributed to the onset of ferromagnetism in specific crystal-surface layers. The bulk ferromagnetism is characterized by the magnetic ordering transition at Curie temperature TC and the transition between two different ferromagnetic phases TFM, accompanied by a structure transition from monoclinic to triclinic symmetry upon cooling. The pressure effects on magnetic parameters were studied with three independent techniques. TC was found to be almost unaffected by pressures up to 0.6 GPa whereas TFM increases rapidly with increasing pressure and reaches TC at a triple point at ~ 0.85 GPa. At higher pressures, only one magnetic phase transition is observed moving to higher temperatures with increasing pressure to reach 99 K at 7.3 GPa. In contrast, the low-temperature bulk magnetization is dramatically reduced by applying pressure (by more than 50% at 2.5 GPa) suggesting a possible pressure-induced reduction of vanadium magnetic moment. We discussed these results in light of recent theoretical studies to analyze exchange interactions and provide how to increase the Curie temperature of VI3.Comment: 20 pages, 16 figure

Honeypots and honeynets: issues of privacy

Honeypots and honeynets are popular tools in the area of network security and network forensics. The deployment and usage of these tools are influenced by a number of technical and legal issues, which need to be carefully considered. In this paper, we outline the privacy issues of honeypots and honeynets with respect to their technical aspects. The paper discusses the legal framework of privacy and legal grounds to data processing. We also discuss the IP address, because by EU law, it is considered personal data. The analysis of legal issues is based on EU law and is supported by discussions on privacy and related issues

ULTRASONIC ATTENUATION IN MIXED STATE OF NIOBIUM

We have investigated the attenuation of ultrasonic waves in the mixed state of niobium, where a remarkable dip appears near the lower critical field . The measurement has been performed on one sample for various orientations of the wave vector and of the principal crystallographic axes of the sample with respect to external magnetic field

Field-induced magnetic ordering in ErNi1-xCuxAl

International audienceThe RNi1-xCuxAl pseudoternaries belong to group of RTX intermetallic compounds crystallizing in the hexagonal ZrNiAl type of structure. In the critical region of the substitution parameter x ~ 0.8 there was found a loss of a long-range magnetic order at the lowest studied temperatures for series with R = Tb, Dy, Er. As an explanation for this effect a competition of different ordering mechanisms for either RNiAl or RCuAl compounds was proposed. Nevertheless, the magnetization curves of the ErNi0.2Cu0.8Al compound (within the critical concentration region) showed behaviour close to the parent ErCuAl, which was confirmed as a ferromagnet. Neutron diffraction on ErNi0.2Cu0.8Al compound with applied magnetic field signifies appearing of the ferromagnetic order at the lowest applied magnetic field of 0.1 T. The magnitude of the ordered magnetic moment increases with increasing magnetic field in agreement with the magnetization curve, confirming tendency to ferromagnetic ordering or short-range magnetic order of ferromagnetic character in this critical region