Magnetization measurements under direct electric currents were performed for toroidal magnetic ordered state of UNi 4 B to test a recent theoretical prediction of current-induced magnetization in a metallic system lacking local inversion symmetry. We found that each of the electric currents parallel to [2110] and [0001] in the hexagonal 4-index notation induces uniform magnetization in the direction of [0110]. The observed behavior of the induced magnetization is essentially consistent with the theoretical prediction; however it also shows an inconsistency suggesting that the antiferromagnetic state of UNi 4 B could not simply be regarded as a uniform toroidal order in the ideal honeycomb layered structure.The behavior of solids without space-inversion symmetry is one of the most attractive topics in the modern condensed matter physics in the last 50 years, since they show interesting phenomena such as a variety of magnetoelectric (ME) effects 1-3) and parity-mixed superconductivity. 4) The intensive studies in the last decade have revealed that an antisymmetric spin-orbit coupling, which becomes active by space-inversion symmetry breaking, plays a relevant role in these phenomena. 5-9) Furthermore, the very recent theoretical and experimental studies have revealed that the various ME effects can be better understood and categorized on the basis of spatially extended odd-parity multipoles, refered to as cluster or itinerant multipoles. [10][11][12] A toroidal moment is the lowest-rank term of toroidal multipole tensors which appear in the multipolar expansion of an electromagnetic vector potential. 13) It can be active in the system without local space-inversion symmetry on the relevant ion sites. In a spin ordered system, the toroidal moment t is defined as the summation of the vector products of position vector r l and spin S l for magnetic sites l: t = gµ B 2 l r l × S l . The summation is taken over appropriate magnetic basis. In a system where toroidal moments order with a ferroic component, both time-reversal and global space-inversion symmetries are broken, and thus macroscopic ME effects can be expected to occur. For example, ME properties seen in high magnetic fields in a traditional multiferroic system Cr 2 O 3 14) and a novel nonreciprocal directional dichroism observed recently in LiCoPO 4 15) are described on the basis of the concept of toroidal order. The toroidal moment has so far been discussed mainly in insulating systems, where r l corresponds to an electric dipole (electric polarization), and the presence of t in a system can easily be recognized.Recently, Hayami et al. have theoretically investigated possible toroidal ordering in a metallic system with broken localinversion symmetry at magnetic-ion sites. 16) They predicted that exotic magnetotransport and ME effects can occur under the toroidal order. Specifically, they performed a mean-field * analysis for a single-band model on a layered honeycomb structure formed by one type of magnetic ion, and show that a ground state with the occurr...

The thermal and electrical transport properties of single-crystalline LaBe 13 have been investigated by specific-heat (C) and electrical-resistivity (ρ) measurements. The specific-heat measurements in a wide temperature range revealed the presence of a hump anomaly near 40 K in the C(T )/T curve, indicating that LaBe 13 has a low-energy Einstein-like-phonon mode with a characteristic temperature of ∼ 177 K. In addition, a superconducting transition was observed in the ρ measurements at the transition temperature of 0.53 K, which is higher than the value of 0.27 K reported previously by Bonville et al. Furthermore, an unusual T 3 dependence was found in ρ(T ) below ∼ 50 K, in contrast to the behavior expected from the electron-electron scattering or the electron-Debye phonon scattering.The beryllides MBe 13 (M = rare earths and actinides) show several novel physical properties depending on the M atom, such as unconventional superconductivity (SC) in UBe 13 , Recently, such cage-structured systems, as represented by filled skutterudites and β-pyrochlores, have been attracting much attention because of the presence of a low-energy

The physical properties of single-crystalline SmBe 13 with a NaZn 13 -type cubic structure have been studied by electrical resistivity (ρ), specific heat (C), and magnetization (M) measurements in magnetic fields of up to 9 T. The temperature (T ) dependence of ρ shows normal metallic behavior without showing the Kondo -lnT behavior, suggesting the weak hybridization effect in this system. Analyses of the temperature dependence of C suggest that the Sm ions of this compound are trivalent and that the crystalline-electric-field (CEF) ground state is a Γ 8 quartet with a first-excited state of a Γ 7 doublet located at the energy scale of ∼ 90 K. Mean-field calculations based on the suggested CEF level scheme can reasonably well reproduce the T dependence of magnetic susceptibility (χ) below ∼ 70 K. These results in the paramagnetic state strongly indicate that the 4 f electrons are well localized with the Sm 3+ configuration. At low temperatures, the 4 f electrons undergo a magnetic order at T M ∼ 8.3 K, where χ(T ) shows an antiferromagnetic-like cusp anomaly. From the positive Curie-Weiss temperature obtained from the mean-field calculations and from a constructed magnetic phase diagram with multiple regions, we discussed the magnetic structure of SmBe 13 below T M , by comparing with other isostructural MBe 13 compounds showing helical-magnetic ordering.

Single-crystalline UAu2Si2 has been grown by a floating-zone melting method, and its magnetic, thermal and transport properties have been investigated through measurements of magnetization, specific heat and electrical resistivity to reveal its peculiar magnetism. It is shown that UAu2Si2 undergoes a second-order phase transition at Tm = 19 K, which had been believed to be ferromagnetic ordering in the literature, from a paramagnetic phase to an uncompensated antiferromagnetic phase with spontaneous magnetization along the tetragonal c-axis (the easy magnetization direction). The magnetic entropy analysis points to the itinerant character of 5f electrons in the magnetic ordered state of UAu2Si2 with large enhancement of the electronic specific heat coefficient of γ ∼ 150 mJ/K 2 mol at 2 K. It also reveals the relatively isotropic crystalline electric field effect of this compound, with contrast to the other relative isostructural compounds. The observed magnetization curves strongly suggest that there is a parasitic ferromagnetic component developing below ∼ 50 K in high coercivity with the easy axis along the tetragonal c-axis. The results are discussed in the context of evolution of magnetism within the entire family of isostructural UT2Si2 compounds. arXiv:1608.06035v2 [cond-mat.str-el]

Low-temperature x-ray crystal structure analysis of the cage-structured compounds MBe 13 (M = La, Sm, and U)