High-pressure structure and electronic properties of YbD to 34 GPa

Klotz, S.*; Casula, M.*; Komatsu, Kazuki*; Machida, Shinichi*; Hattori, Takanori

Physical Review B, 100(2), p.020101_1 - 020101_5, 2019/07

https://doi.org/10.1103/PhysRevB.100.020101

Ytterbium dihydride (YbH) shows a well-known transition at 16 GPa from a CaH-type structure to a high-pressure (high-) phase with Yb at hcp sites and unknown H-positions. Here, we report its complete structure determination by neutron diffraction at 34 GPa. Hydrogen(deuterium) is located at 2 and 2 positions of space group , thus forming a high-symmetry "collapsed" close-packed lattice. The transition is sluggish and can be seen as a transfer of 1/2 of the hydrogen atoms from strongly corrugated H-layers to interstitial sites of the Yb-lattice. We demonstrate by first-principles calculations that the transition is related to a change from a completely filled -electron conguration to a fractional -hole (0.25 h) occupation in the high- phase. The charge transfer closes the gap at the transition and leads to a metallic ground state with sizeable electron-phonon interaction involving out-of-plane vibrational modes of interstitial hydrogen.

Quantum dynamics of hydrogen in the iron-based superconductor LaFeAsOD measured with inelastic neutron spectroscopy

Yamaura, Junichi*; Hiraka, Haruhiro*; Iimura, Soshi*; Muraba, Yoshinori*; Bang, J.*; Ikeuchi, Kazuhiko*; Nakamura, Mitsutaka; Inamura, Yasuhiro; Honda, Takashi*; Hiraishi, Masatoshi*; et al.

Physical Review B, 99(22), p.220505_1 - 220505_6, 2019/06

https://doi.org/10.1103/PhysRevB.99.220505

Inelastic neutron scattering was performed for an iron-based superconductor , where most of D (deuterium) replaces oxygen, while a tiny amount goes into interstitial sites. By first-principle calculation, we characterize the interstitial sites for D (and for H slightly mixed) with four equivalent potential minima. Below the superconducting transition temperature Tc = 26 K, new excitations emerge in the range 5-15 meV, while they are absent in the reference system LaFeAsOF. The strong excitations at 14.5 meV and 11.1 meV broaden rapidly around 15 K and 20 K, respectively, where each energy becomes comparable to twice of the superconducting gap. The strong excitations are ascribed to a quantum rattling, or a band motion of hydrogen, which arises only if the number of potential minima is larger than two.

Fusion reaction Ca+Bk leading to formation of the element Ts (Z=117)

Khuyagbaatar, J.*; Yakushev, A.*; Dllmann, Ch. E.*; Ackermann, D.*; Andersson, L.-L.*; Asai, Masato; Block, M.*; Boll, R. A.*; Brand, H.*; Cox, D. M.*; et al.

Physical Review C, 99(5), p.054306_1 - 054306_16, 2019/05

https://doi.org/10.1103/PhysRevC.99.054306

We have performed an experiment to synthesize the element 117 (Ts) with the Ca+Bk fusion reaction. Four -decay chains attributed to the element 117 were observed. Two of them were long decay chains which can be assigned to the one originating from the decay of Ts. The other two were short decay chains which are consistent with the one originating from the decay of Ts. We have compared the present results with the literature data, and found that our present results mostly confirmed the literature data, leading to the firm confirmation of the synthesis of the element 117.

Topological characterization of classical waves; The Topological origin of magnetostatic surface spin waves

Yamamoto, Kei; Thiang, G. C.*; Pirro, P.*; Kim, K.-W.*; Everschor-Sitte, K.*; Saito, Eiji*

Physical Review Letters, 122(21), p.217201_1 - 217201_5, 2019/05

https://doi.org/10.1103/PhysRevLett.122.217201

Negative Te spin polarization responsible for ferromagnetic order in the doped topological insulator V(SbBi)Te

Ye, M.*; Xu, T.*; Li, G.*; Qiao, S.*; Takeda, Yukiharu; Saito, Yuji; Zhu, S.-Y.*; Nurmamat, M.*; Sumida, Kazuki*; Ishida, Yukiaki*; et al.

Physical Review B, 99(14), p.144413_1 - 144413_7, 2019/04

http://dx.doi.org/10.1103/PhysRevB.99.144413

Novel critical behavior of magnetization in URhSi; Similarities to the uranium ferromagnetic superconductors UGe and URhGe

Tateiwa, Naoyuki; Haga, Yoshinori; Yamamoto, Etsuji

Physical Review B, 99(9), p.094417_1 - 094417_12, 2019/03

http://dx.doi.org/10.1103/PhysRevB.99.094417

We study the critical behavior of dc magnetization in the uranium ferromagnet URhSi around the ferromagnetic phase transition at 10 K. The critical exponent for the spontaneous magnetization below , for the magnetic susceptibility, and for the magnetic isotherm at have been determined as = 0.300 0.002, = 1.00 0.02, and = 4.32 0.04 by the scaling analysis and the critical isotherm analysis. Magnetization has strong uniaxial magnetic anisotropy in the ferromagnetic state of URhSi. However, the universality class of the critical phenomenon does not belong to the 3D Ising system ( = 0.325, = 1.241, and = 4.82). The obtained exponents in URhSi are similar to those in uranium ferromagnetic superconductors UGe and URhGe. We discuss the static and dynamical magnetic properties of URhSi in comparison with those in UGe, URhGe and UCoGe.

High-field phase diagram of the heavy-fermion metal CeIn; Pulsed-field NMR study on single crystals up to 56 T

Tokunaga, Yo; Orlova, A.*; Bruyant, N.*; Aoki, Dai*; Mayaffre, H.*; Krmer, S.*; Julien, M.-H.*; Berthier, C.*; Horvati, M.*; Higa, Nonoka; et al.

Physical Review B, 99(8), p.085142_1 - 085142_5, 2019/02

http://dx.doi.org/10.1103/PhysRevB.99.085142

The heavy-fermion antiferromagnet CeIn exhibits a field-induced anomaly associated with Fermi surface reconstruction at 45 T, well below the antiferromagnetic (AFM) critical field that exceeds 60 T. In order to explore the origin of this anomaly, we have measured In NMR spectra in pulsed magnetic fields up to 56 T using high-quality single crystals. To within experimental resolution, we do not detect any change in the NMR spectra that could suggest a modification in either the character of the hyperfine field or the electric field gradient at In sites through . This strongly suggests that the 45 T anomaly cannot be simply ascribed to a field-induced change in the magnetic structure of the AFM state.

Magnetic and electrical properties of the ternary compound UIrSi with one-dimensional uranium zigzag chains

Li, D. X.*; Honda, Fuminori*; Miyake, Atsushi*; Homma, Yoshiya*; Haga, Yoshinori; Nakamura, Ai*; Shimizu, Yusei*; Maurya, A.*; Sato, Yoshiki*; Tokunaga, Masashi*; et al.

Physical Review B, 99, p.054408-1 - 054408-9, 2019/01

https://doi.org/10.1103/PhysRevB.99.054408

Spin correlations of quantum spin liquid and quadrupole-ordered states of TbTiO

Kadowaki, Hiroaki*; Wakita, Mika*; Fk, B.*; Ollivier, J.*; Kawamura, Seiko; Nakajima, Kenji; Lynn, J. W.*

Physical Review B, 99(1), p.014406_1 - 014406_12, 2019/01

https://doi.org/10.1103/PhysRevB.99.014406

Spin correlations of the frustrated pyrochlore oxide TbTiO have been investigated by using inelastic neutron scattering on single-crystalline samples (x = -0.007, 0.000, and 0.003), which have the putative quantum-spin-liquid (QSL) or electric-quadrupolar ground states. Spin correlations, which are notably observed in nominally elastic scattering, show short-range correlations around points, tiny antiferromagnetic Bragg scattering at L and points, and pinch-point-type structures around points. The short-range spin correlations were analyzed using a random-phase approximation (RPA) assuming the paramagnetic state and two-spin interactions among Ising spins. These analyses have shown that the RPA scattering intensity well reproduces the experimental data using temperature- and x-dependent coupling constants of up to tenth-neighbor site pairs. This suggests that no symmetry breaking occurs in the QSL sample and that a quantum treatment beyond the semiclassical RPA approach is required. Implications of the experimental data and the RPA analyses are discussed.

-factor measurement of the 2738 keV isomer in La

Laskar, Md. S. R.*; Saha, S.*; Palit, R.*; Mishra, S. N.*; Shimizu, Noritaka*; Utsuno, Yutaka; Ideguchi, Eiji*; Naik, Z.*; Babra, F. S.*; Biswas, S.*; et al.

Physical Review C, 99(1), p.014308_1 - 014308_6, 2019/01

http://dx.doi.org/10.1103/PhysRevC.99.014308

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