波紋
Online ISSN : 1884-636X
Print ISSN : 1349-046X
ISSN-L : 1349-046X
最新号
選択された号の論文の5件中1~5を表示しています
サイエンス記事
  • 高津 浩
    2017 年 27 巻 4 号 p. 140-143
    発行日: 2017年
    公開日: 2018/11/14
    ジャーナル フリー

    A hidden order that emerges in the frustrated pyrochlore Tb2+xTi2-xO7+y with Tc = 0.53 K is studied using neutron scattering, specific heat, magnetization measurements on a high-quality single crystal. Semiquantitative analyses based on a pseudospin-1/2 Hamiltonian for ionic non-Kramers magnetic doublets demonstrate that it is a long-range order of electric quadrupole moments intrinsic to the Tb3+ ions. This is the first example of electric quadrupole order in frustrated magnetic systems, and opens new research directions for "frustrated quadrupole systems". It is also found that the elusive spin liquid state of the nominal Tb2Ti2O7, studied for more than a decade, is most likely a U(1) quantum spin-liquid state.

  • 鬼丸 孝博, 岩佐 和晃
    2017 年 27 巻 4 号 p. 144-147
    発行日: 2017年
    公開日: 2018/11/14
    ジャーナル フリー

    A cubic 4f2 system PrIr2Zn20 exhibits a superconducting transition at 0.05 K below a quadrupolar transition at 0.11 K. We have conducted neutron diffraction measurements in magnetic fields B ≤ 5 T down to 0.04 K to determine the order parameter expected for the non-Kramers ground state doublet. Field-induced magnetic reflection appears at Q = (1/2, 1/2, –3/2) together with some of its equivalents in B || [1 −1 0]. Thus, the antiferroquadrupole order is characterized by the propagation vector q = (1/2, 1/2, 1/2). The magnetic-structure-factor analysis revealed that the magnetic moments are induced along the [1 1 1] axis on the Pr-ion diamond sublattice. In contrast, no reflections appear for B || [0 0 1] as well as in zero field. The results indicate that the O22-type quadrupole is the primary order parameter which entangles with other various multipolar degrees of freedom. Such entanglements should play the role in the enriched B-T phase diagram of PrIr2Zn20 including the non-Fermi liquid state and field-induced Fermi liquid state.

技術ノート
入門講座「中性子のつくりかた」
feedback
Top