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Unconventional superconductors have Cooper pairs with lower symmetries than in conventional superconductors. In most unconventional superconductors, the additional symmetry breaking occurs in relation to typical ingredients such as strongly correlated Fermi liquid phases, magnetic fluctuations, or strong spin-orbit coupling in noncentrosymmetric structures. In this article, we show that the time-reversal symmetry breaking in the superconductor LaNiGa2 is enabled by its previously unknown topological electronic band structure, with Dirac lines and a Dirac loop at the Fermi level. Two symmetry related Dirac points even remain degenerate under spin-orbit coupling. These unique topological features enable an unconventional superconducting gap in which time-reversal symmetry can be broken in the absence of other typical ingredients. Our findings provide a route to identify a new type of unconventional superconductors based on nonsymmorphic symmetries and will enable future discoveries of topological crystalline superconductors. Topological superconducting systems are expected to exhibit a range of exotic physics which are particularly useful for application in quantum computing technologies. Here, the authors report the synthesis of LaNiGa2 which exhibits both topological and superconducting features originating from its nonsymmorphic crystal structure. [ABSTRACT FROM AUTHOR]

A new rare earth metal Zintl phase, Eu3In2P4 is synthesized by utilizing a metal flux method. At the magnetic ordering temperature, this compound shows a negative magnetoresistance and there are two crystallographically different Eu(super 2) sites in this compound.

Eu3InP3 is prepared as large single crystals with an indium flux reaction. The temperature dependence of the conductivity indicates that Eu3InP3 is a small band gap semiconductor.

Research has been conducted on transitio-metal-containing Zintl compound Eu (sub)10 Mn (sub)6 Sb (sub)13. The authors describe the preparation of this compound via high-temperature tin-flux synthesis, and report that its structure has been investigated via the use of single-crystal X-ray diffraction.

Nuclear spin relaxation rates of 2H and 139La in LaCl3+2H2O and La(ClO4)3+2H2O solutions were determined as a function of pressure in order to demonstrate a new NMR probe designed for solution spectroscopy at geochemical pressures. The 2H longitudinal relaxation rates (T1) vary linearly to 1.6 GPa, consistent with previous work at lower pressures. The 139La T1 values vary both with solution chemistry and pressure, but converge with pressure, suggesting that the combined effects of increased viscosity and enhanced rates of ligand exchange control relaxation. This simple NMR probe design allows experiments on aqueous solutions to pressures corresponding roughly to those at the base of the Earth's continental crust. [ABSTRACT FROM AUTHOR]

A non-magnetic piston-cylinder pressure cell is presented for solution-state NMR spectroscopy at geochemical pressures. The probe has been calibrated up to 20 kbar using in situ ruby fluorescence and allows for the measurement of pressure dependencies of a wide variety of NMR-active nuclei with as little as 10 μL of sample in a microcoil. Initial 11B NMR spectroscopy of the H3BO3-catechol equilibria reveals a large pressure-driven exchange rate and a negative pressure-dependent activation volume, reflecting increased solvation and electrostriction upon boron-catecholate formation. The inexpensive probe design doubles the current pressure range available for solution NMR spectroscopy and is particularly important to advance the field of aqueous geochemistry. [ABSTRACT FROM AUTHOR]

The Zintl phase Yb14MnSb11was successfully doped with Ge utilizing a tin flux technique. The stoichiometry was determined by microprobe analysis to be Yb13.99(14)Mn1.05(5)Sb10.89(16)Ge0.06(3). This was the maximum amount of Ge that could be incorporated into the structure viaflux synthesis regardless of the amount included in the reaction. Single crystal X-ray diffraction could not unambiguously determine the site occupancy for Ge. Bond lengths varied by about 1% or less, compared with the undoped structure, suggesting that the small amount of Ge dopant does not significantly perturb the structure. Differential scanning calorimetry/thermogravimetry (DSC/TG) show that the doped compound's melting point is greater than 1200 K. The electrical resistivity and magnetism are virtually unchanged from the parent material, suggesting that Yb is present as Yb2+and that the Ge dopant has little effect on the magnetic structure. At 900 K the resistivity and Seebeck coefficient decrease resulting in a zT of 0.45 at 1100 K, significantly lower than the undoped compound. [ABSTRACT FROM AUTHOR]

The article discusses a study which examined the flux growth and crystal structure of two inorganic compounds with the Euln2P2 with the structure type, AIn2P2 and a structure type, BaIn2P2. It investigates the synthesis of calcium indium phosphide, strontium indium phosphide and barium indium phosphide from a reactive indium flux. Also observed are the temperature-dependent magnetoresistance and magneto-optical behavior as well as the alkaline earth analogs of the compound.

Large, high quality single crystals of a new Zintl phase, Euln2As2, have been synthesized from a reactive indium flux. Euln2As2 is isostructural to the recently reported phase Euln2P2, and it is only the second reported member of the group of compounds with formula AM2X2 (A = alkali, alkaline earth, or rare earth cation; M = transition or post-transition metal; and X = Group 14 or 15 element) that crystallizes in the hexagonal space group P63/mmc (a = 4.2067(3) Å, c = 17.889(2) Å and Z = 2). The structure type contains layers of A2+ cations separated by [M2X2]2- layers along the crystallographic c-axis. Crystals of the title compound were mounted for magnetic measurements, with the crystallographic c-axis oriented either parallel or perpendicular to the direction of the applied field. The collective magnetization versus temperature and field data indicate two magnetic exchange interactions near 16 K, one involving Eu2+ … Eu2+ intralayer coupling and the other involving Eu2+ …. Eu2+ coupling between layers. Euln2As2 is metallic and magnetoresistive, as is the isostructural phosphide, and both compounds have coincident resistivity and magnetic ordering transitions, consistent with the observation of colossal magnetoresistance. Negative colossal magnetoresistance (MR = {[ρ(H) - ρ(0)/ρ(H) x 100% of up to -143% (at T = 17.5 K, H = 5 T) is Observed for Euln2As2, approximately half of that observed for the more resistive phosphide, which has a higher magnetic ordering temperature and local moment coupling strength. [ABSTRACT FROM AUTHOR]

A correction to the article "²H and 139La NMR Spectroscopy in Aqueous Solutions at Geochemical Pressures" that was published in the 2015 issue is presented.

Geochemical models for aqueous solution equilibria extend to pressures and temperatures well beyond experimental spectroscopies that could test the predictions. W. H. Casey and co‐workers describe in their Communication on page 9788 ff. a simple NMR probe that can allow spectroscopy on solutions at pressures near those of the Earth's continental crust. (Greg Pautler Graphic Design, Ontario, Canada, is thanked for designing and donating the artwork.) [ABSTRACT FROM AUTHOR]

Die geochemischen Modelle chemischer Gleichgewichte in wässriger Lösung reichen oft über die zugänglichen Druck ‐ und Temperaturbereiche verfügbarer Spektroskopien hinaus. W. H. Casey et al. beschreiben in der Zuschrift auf S. 9946 ff. nun eine einfache NMR ‐ Sonde, die die spektroskopische Untersuchung von Lösungen bei Drücken ähnlich denen im Innern der Erdkruste ermöglicht (Greg Pautler Graphik Design, Ontario). [ABSTRACT FROM AUTHOR]

Nuclear-magnetic resonance (NMR) spectra of CsCl and LaCl 3 in D 2 O/H 2 O solutions were collected up to pressures of 1.9 GPa using a new NMR probe design that considerably extends the pressure range available for geochemical experiments. The longitudinal-relaxation times ( T 1 ) for 2 H compare well with those reported in the previous studies of Lee et al. (1974), who examined lower pressures, and indicate that the probe functions properly. In some experiments, 133 Cs and 1 H NMR spectra could be taken on solutions to pressures well beyond the nominal freezing pressure of D 2 O or H 2 O to form Ice VI (near 0.9 GPa). Freezing to form the high-pressure ice is kinetically slow on an experimental time scale (minutes to hours). The data indicate that the electrolyte concentrations increase the freezing pressure of the solution. This result means that solution NMR spectra can be collected at pressures that are nearly twice the nominal freezing pressure of pure D 2 O or H 2 O. Pulsed-magnetic-field-gradient NMR methods are used to independently measure the self-diffusion coefficient of H 2 O in these solutions, which yields estimates of solution viscosity via the Stokes–Einstein relation. The increased viscosity accounts for the pressure variation of T 1 values as rates of molecular tumbling are affected. Accounting for such changes is essential if NMR spectral line widths are used to infer pressure-enhanced rates of geochemical reactions, such as interconversion of aqueous complexes. [ABSTRACT FROM AUTHOR]

Single-crystalline samples of a new Zintl compound, Eu3Ga2P4, have been synthesized by a Ga-flux method. Eu3Ga2P4 is found to crystallize in a monoclinic unit cell, space group C2/c, isostructural to Ca3Al2As4. The structure is composed of a pair of edge-shared GaP4 tetrahedra, which link by corner-sharing to form Ga2P4 two-dimensional layers, separated by Eu2+ ions. Magnetic susceptibility showed a Curie-Weiss behavior with an effective magnetic moment consistent with the value for Eu2+ magnetic ions. Below 15 K, ferromagnetic ordering was observed and the saturation magnetic moment was 6.6 μB. Electrical resistivity measurements on a single crystal showed semiconducting behavior. Resistivity in the temperature range between 280 and 300 K was fit by an activation model with an energy gap of 0.552(2) eV. The temperature dependence of the resistivity is better described by the variable-range-hopping model for a three-dimensional conductivity, suggesting that Eu-P bonds are involved in the conductivity. A large magnetoresistance, up to −30%, is observed with a magnetic field H = 2 T at T = 100 K, suggesting strong coupling of carriers with the Eu2+ magnetic moment. [ABSTRACT FROM AUTHOR]

Unconventional superconductors have Cooper pairs with lower symmetries than in conventional superconductors. In most unconventional superconductors, the additional symmetry breaking occurs in relation to typical ingredients such as strongly correlated Fermi liquid phases, magnetic fluctuations, or strong spin-orbit coupling in noncentrosymmetric structures. In this article, we show that the time-reversal symmetry breaking in the superconductor LaNiGa2 is enabled by its previously unknown topological electronic band structure, with Dirac lines and a Dirac loop at the Fermi level. Two symmetry related Dirac points even remain degenerate under spin-orbit coupling. These unique topological features enable an unconventional superconducting gap in which time-reversal symmetry can be broken in the absence of other typical ingredients. Our findings provide a route to identify a new type of unconventional superconductors based on nonsymmorphic symmetries and will enable future discoveries of topological crystalline superconductors. Topological superconducting systems are expected to exhibit a range of exotic physics which are particularly useful for application in quantum computing technologies. Here, the authors report the synthesis of LaNiGa2 which exhibits both topological and superconducting features originating from its nonsymmorphic crystal structure. [ABSTRACT FROM AUTHOR]

We report 139La nuclear magnetic resonance data in La4Ni3O8 that reveal the presence of antiferromagnetic order below TN~105 K. This remarkable compound contains two-dimensional (2D) layers of NiO2 with unusual Ni valences. La4Ni3O8, with antiferromagnetic order of S=1/2 Ni1+ spins, is analogous to the parent compounds of the cuprate superconductors. Our data clearly reveal dramatic spectral changes and low-energy antiferromagnetic correlations associated with the onset of long-range order below TN. These critical spin fluctuations, however, do not diverge at the second-order phase transition but rather appear to be associated with a T=0 transition characteristic of 2D spin fluctuations. [ABSTRACT FROM AUTHOR]

The article discusses a study which examined the flux growth and crystal structure of two inorganic compounds with the Euln2P2 with the structure type, AIn2P2 and a structure type, BaIn2P2. It investigates the synthesis of calcium indium phosphide, strontium indium phosphide and barium indium phosphide from a reactive indium flux. Also observed are the temperature-dependent magnetoresistance and magneto-optical behavior as well as the alkaline earth analogs of the compound.

Abstract: Ln 3Co4Sn13 (Ln=La, Ce) have been synthesized by flux growth and characterized by single crystal X-ray diffraction. These compounds adopt the Yb3Rh4Sn13-type structure and crystallize in the cubic space group (No. 223) with . Lattice parameters at 298K are , , and , for the La and Ce analogues, respectively. The crystal structure consists of an Sn-centered icosahedron at the origin of the unit cell, which shares faces with eight Co trigonal prisms and 12 Ln-centered cuboctahedra. Magnetization data at 0.1T show paramagnetic behavior down to 1.8K for Ce3Co4Sn13, with per Ce3+, while conventional type II superconductivity appears below 2.85K in the La compound. Electrical resistivity and specific heat data for the La compound show a corresponding sharp superconducting transition at T c∼2.85K. The entropy and resistivity data for Ce3Co4Sn13 show the existence of the Kondo effect with a complicated semiconducting-like behavior in the resistivity data. In addition, a large enhanced specific heat coefficient at low T with a low magnetic transition temperature suggests a heavy-fermionic character for the Ce compound. Herein, the structure and physical properties of Ln 3Co4Sn13 (Ln=La, Ce) are discussed. [Copyright &y& Elsevier]