The results of a single-crystal X-ray-diffraction study of the evolution of crystal structures of VI3 with temperature with emphasis on phase transitions are presented. Some related specific-heat and magnetization data are included. The existence of the room-temperature trigonal crystal structure R-3 (148) has been confirmed. Upon cooling, VI3 undergoes a structural phase transition to a monoclinic phase at Ts ~ 79 K. Ts is reduced in magnetic fields applied along the trigonal c-axis. When VI3 becomes ferromagnetic at TFM1 ~ 50 K, magnetostriction-induced changes of the monoclinic-structure parameters are observed. Upon further cooling, the monoclinic structure transforms into a triclinic variant at 32 K which is most likely occurring in conjunction with the previously reported transformation of the ferromagnetic structure. The observed phenomena are preliminarily attributed to strong magnetoelastic interactions.

A prototypical quasi-2D metallic compound, 1T-TaS 2 has been extensively studied due to an intricate interplay between a Mottinsulating ground state and a charge-density-wave order. In the low-temperature phase, 12 out of 13 Ta 4+ 5d-electrons form molecular orbitals in hexagonal star-of-David patterns, leaving one 5d-electron with S = ½ spin free. This orphan quantum spin with a large spin-orbit interaction is expected to form a highly correlated phase of its own. And it is most likely that they will form some kind of a short-range order out of a strongly spin-orbit coupled Hilbert space. In order to investigate the low-temperature magnetic properties, we performed a series of measurements including neutron scattering and muon experiments. The obtained data clearly indicate the presence of the short-ranged phase and put the upper bound on~0.4 µ B for the size of the magnetic moment, consistent with the orphan-spin scenario.npj Quantum Materials (2017)2:42 ; doi:10.1038/s41535-017-0048-1 INTRODUCTIONThe instability of charge density waves (CDW) found in lowdimensional electron systems of layered materials has attracted enormous attention recently. 1T-TaS 2 is a prototypical quasi-2D metallic compound with a strong electron-phonon coupling responsible often for CDW instabilities. Upon cooling, it undergoes a series of first-order phase transitions to CDW, Mott and superconducting phases (see e.g., ref. 1 and references therein).1T-TaS 2 bulk crystal has a lamellar structure, with each layer composed of a triangular lattice of Ta atoms which is then sandwiched by S atoms in an octahedral TaS 6 coordination with a weak Van der Waals bonding between the layers. Above~540 K, the structure is unmodulated trigonal with P-3m1 symmetry; below which the triangular lattice exhibits a series of structural modulations.2, 3 First, an incommensurate CDW phase sets in at T 540 K. Upon further cooling, the structure changes to a nearly commensurate phase at T nCDW~3 50 K. Finally, the material turns into a Mott insulating phase with in-plane √13 × √13 superlattice distortion, which coexists with a commensurate CDW phase below T CDW~1 80 K. Superconductivity emerges in 1T-TaS 2 below~2 K by introducing disorders.4 Recent angle-resolved photoemission spectroscopy experiments suggest that the melted Mott state and the superconductivity coexist in real space 5 providing better understanding of the interplay between electron correlation, charge order, and superconductivity. Unlike other Mott insulators, the CDW superlattices play the role of localization centers in the ground state of 1T-TaS 2 .According to the current understanding, the CDW phase is composed of molecular orbitals of 13 Ta atoms, forming a hexagonal pattern of so-called David-star clusters. As proposed more than three decades ago, 6 each Ta 4+ of 1T-TaS 2 provides one 5d electron, and thus there are 13 5d-electrons per each David star. Out of these 13 electrons, 12 electrons form 6 covalent bonds

We report on single crystal growth and crystallographic parameters results of Ce 2 PdIn 8 , Ce 3 PdIn 11, Ce 2 PtIn 8 and Ce 3 PtIn 11 . The Pt-systems Ce 2 PtIn 8 and Ce 3 PtIn 11 are synthesized for the first time. All these compounds are member of the Ce n T m In 3n+2m (n = 1, 2,..; m = 1, 2,.. and T = transition metal) to which the extensively studied heavy fermion superconductor CeCoIn 5 belongs. Single crystals have been grown by In self-flux method. Differential scanning calorimetry studies were used to derive optimal growth conditions. Evidently, the maximum growth conditions for these materials should not exceed 750 °C. Single crystal x-ray data show that Ce 2 TIn 8 compounds crystallize in the tetragonal Ho 2 CoGa 8 phase (space group P4/mmm) with lattice parameters a =4.6898(3) Å and c =12.1490(8) Å for the Pt-based one (Pd: a = 4.6881(4) Å and c = 12.2031(8) Å). The Ce 3 TIn 11 compounds adopt the Ce 3 PdIn 11 structure with a = 4.6874(4) Å and c = 16.8422(12) Å for the Pt-based one (Pd: a = 4.6896 Å and c = 16.891 Å). Specific heat experiments on Ce 3 PtIn 11 and Ce 3 PdIn 11 have revealed that both compounds undergo two successive magnetic transitions at T 1 ~ 2.2 K followed by T N ~ 2.0 K and T 1 ~ 1.7 K and T N ~ 1.5 K, respectively. Additionally, both compounds exhibit enhanced Sommerfeld coefficients yielding γ Pt = 0.300 J/mol K 2 Ce (γ Pd = 0.290 J/mol K 2 Ce), hence qualifying them as heavy fermion materials.

Many current research efforts in strongly correlated systems focus on the interplay between magnetism and superconductivity. Here we report on coexistence of both cooperative ordered states in recently discovered stoichiometric and fully inversion symmetric heavy fermion compound Ce3PdIn11 at ambient pressure. Thermodynamic and transport measurements reveal two successive magnetic transitions at T1 = 1.67 K and TN = 1.53 K into antiferromagnetic type of ordered states. Below Tc = 0.42 K the compound enters a superconducting state. The large initial slope of dBc2/dT ≈ – 8.6 T/K indicates that heavy quasiparticles form the Cooper pairs. The origin of the two magnetic transitions and the coexistence of magnetism and superconductivity is briefly discussed in the context of the coexistence of the two inequivalent Ce-sublattices in the unit cell of Ce3PdIn11 with different Kondo couplings to the conduction electrons.

The properties of the novel heavy fermion superconductor Ce3PtIn11 are investigated by thermodynamic and transport measurements at ambient and under hydrostatic pressure. At ambient pressure the compound exhibits two successive magnetic transitions at T1 ≃ 2.2 K and TN ≃ 2 K into antiferromagnetically ordered states and enters into a heavy fermion superconducting phase below Tc ≃ 0.32 K. The coexistence of long-range magnetic order and superconductivity is discussed in the context of the existence of the two crystallographically inequivalent Ce-sites in the unit cell of Ce3PtIn11. The experimental data allow us to construct the pressure-temperature phase diagram.

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In this paper, specific features of Sm magnetism in an intermetallic compound have been studied.For this purpose, a high quality single crystal of SmPd 2 Al 3 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. T, as detected in the 1.8-K magnetization data. The temperature dependence of the paramagnetic susceptibility below 200 K can be in the first approximation interpreted in terms of a Curie-Weiss law modified by temperature independent van Vleck contribution due to the low-lying first excited multiplet J = 7/2 being populated. At higher temperatures, involvement of the second excited multiplet J = 9/2 should also be considered. 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 SmPd 2 Al 3 compound.

We present the ultra-low-temperature thermal conductivity measurements on single crystals of the prototypical charge-density-wave material 1T -TaS2, which was recently argued to be a candidate for quantum spin liquid. Our experiments show that the residual linear term of thermal conductivity at zero field is essentially zero, within the experimental accuracy. Furthermore, the thermal conductivity is found to be insensitive to the magnetic field up to 9 T. These results clearly demonstrate the absence of itinerant magnetic excitations with fermionic statistics in bulk 1T -TaS2 and, thus, put a strong constraint on the theories of the ground state of this material.