Browsing by Author "Kurita, N"

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    Magnetic structure of the S=1/2 quasi-two-dimensional square-lattice Heisenberg antiferromagnet Sr2CuTeO6
    (American Physical Society, 2016-02-26) Koga, T; Kurita, N; Avdeev, M; Danilkin, SA; Sato, TJ; Tanaka, H
    The magnetic structure of the double perovskite compound Sr2CuTeO6 was determined from neutron powder diffraction data. This material is magnetically described as an S=1/2 quasi-two-dimensional square-lattice Heisenberg model with antiferromagnetic nearest-neighbor and next-nearest-neighbor interactions. Sr2CuTeO6 undergoes a magnetic phase transition at TN≃29 K. The spin structure below TN is Néel antiferromagnetic on the square lattice, which means that the nearest-neighbor interaction (J1) is stronger than the next-nearest-neighbor interaction (J2), in contrast to other isostructural compounds such as Ba2CuWO6 and Sr2CuWO6, for which |J1|<|J2| is realized. ©2016 American Physical Society
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    Quantum magnetic properties of the spin-1/2 triangular-lattice antiferromagnet Ba2La2CoTe2O12
    (American Physical Society, 2018-11-05) Kojima, Y; Watanabe, M; Kurita, N; Tanaka, H; Matsuo, A; Kindo, K; Avdeev, M
    We report the crystal structure of Ba2La2CoTe2O12 determined by Rietveld analysis using x-ray powder-diffraction data. It was found from magnetic measurements that Ba2La2CoTe2O12 can be described as a spin-12 triangular-lattice antiferromagnet with easy-plane anisotropy at low temperatures. This compound undergoes a magnetic phase transition at TN=3.26K to an ordered state with the 120∘ structure. The magnetization curve exhibits the one-third plateau characteristic of triangular-lattice quantum antiferromagnets. The antiferromagnetic exchange interaction and the g factors parallel and perpendicular to the c axis were evaluated to be J/kB=22K,g∥=3.5, and g⊥=4.5, respectively. ©2018 American Physical Society
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    Successive phase transitions and magnetization plateau in the spin-1 triangular-lattice antiferromagnet Ba2La2NiTe2O12 with small easy-axis anisotropy
    (American Physical Society, 2019-08-22) Saito, M; Watanabe, M; Kurita, N; Matsuo, A; Kindo, K; Avdeev, M; Jeschke, HO; Tanaka, H
    The crystal structure and magnetic properties of the spin-1 triangular-lattice antiferromagnet Ba2La2NiTe2O12 are reported. Its crystal structure is trigonal R¯3, which is the same as that of Ba2La2NiW2O12 [Y. Doi et al., J. Phys.: Condens. Matter 29, 365802 (2017)]. However, the exchange interaction J/kB≃19 K is much greater than that observed in the tungsten system. At zero magnetic field, Ba2La2NiTe2O12 undergoes successive magnetic phase transitions at TN1=9.8 K and TN2=8.9 K. The ground state is accompanied by a weak ferromagnetic moment. These results indicate that the ground-state spin structure is a triangular structure in a plane perpendicular to the triangular lattice owing to the small easy-axis-type anisotropy. The magnetization curve exhibits the one-third plateau characteristic of a two-dimensional triangular-lattice Heisenberg-like antiferromagnet. Exchange constants are also evaluated using density functional theory (DFT). The DFT results demonstrate the large difference in the exchange constants between tellurium and tungsten systems and the good two-dimensionality of the tellurium system. ©2019 American Physical Society