Browsing by Author "Murasaki, R"

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    Antiferromagnetic order of ferromagnetically coupled dimers in the double pyrovanadate CaCoV2O7
    (Cornell University, 2021-08-02) Murasaki, R; Nawa, K; Okuyama, D; Avdeev, M; Sato, TJ
    Magnetic properties of the pyrovanadate CaCoV2O7 have been studied by means of the bulk magnetization and neutron powder diffraction measurements. Magnetic susceptibility in the paramagnetic phase shows Curie-Weiss behavior with negative Weiss temperature ≃ −22.5 K, indicating dominant antiferromagnetic interactions. At TN = 3.44 K, CaCoV2O7 shows antiferromagnetic order, accompanied by a weak net ferromagnetic moment of ∼ 0.05 μB/Co2+. Neutron powder diffraction confirms the formation of antiferromagnetic order below TN. It was further confirmed from the magnetic structure determination that the two Co2+ ions in the adjacent edge-sharing octahedra have almost parallel (ferromagnetic) spin arrangement, indicative of a formation of a ferromagnetic spin dimer. The antiferromagnetic order is, in turn, stabilized by sizable inter-dimer antiferromagnetic interactions.
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    Magnetic properties of the quasicrystal approximant Au65Ga21Tb14
    (American Physical Society, 2023-05-31) Nawa, K; Avdeev, M; Ishikawa, A; Takakura, H; Wang, CW; Tamura, R; Okuyama, D; Satao, TJ; Murasaki, R
    The magnetic properties of the quasicrystal approximant Au65Ga21Tb14 were investigated using magnetization and neutron diffraction experiments. The temperature dependences of the magnetic susceptibility and magnetization curve indicate dominant ferromagnetic interactions, whereas a whirling antiferromagnetic order was observed in neutron diffraction experiments. In the antiferromagnetic phase, the magnetic moments are aligned almost perpendicular to a pseudofivefold symmetry axis, which corresponds to the easy-axis direction of a Tb atom. Magnetic properties similar to those of Au72Al14Tb14 in spite of the substantial difference in the Au concentration suggest the robustness of the easy-axis anisotropy against the chemical environment. ©2023 American Physical Society