Collinear order in frustrated quantum antiferromagnet on square lattice (CuBr)LaNb2O7

Noriaki Oba, Hiroshi Kageyama, Taro Kitano, Jun Yasuda, Yoichi Baba, Masakazu Nishi, Kazuma Hirota, Yasuo Narumi, Masayuki Hagiwara, Koichi Kindo, Takashi Saito, Yoshitami Ajiro, Kazuyoshi Yoshimura

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39 Citations (Scopus)


Magnetic susceptibility, heat capacity, high-field magnetization and neutron diffraction measurements have been performed on a two-dimensional S = 1/2 square-lattice system (CuBr)LaNb2O7, prepared by a topotactic ion-exchange reaction of a nonmagnetic double-layered perovskite RbLaNb2O7. (CuBr)LaNb2O7 exhibits a second-order magnetic transition at 32 K, in marked contrast to a spin-singlet nature for its Cl-based counterpart (CuCl)LaNb2O7, despite nearly identical structural parameters. The magnetic structure is a novel collinear antiferromagnetic (CAF) ordering characterized by a modulation vector q = (π, 0, π) with a reduced moment of 0.6μB. Mixed ferromagnetic nearest-neighbor (J1) and antiferromagnetic second-nearest-neighbor (J2) interactions are of comparable strength (J1/kB = -35.6K and J2=kB = 41.3 K), placing the system in a more frustrated region of the CAF phase than ever reported.

Original languageEnglish
Article number113601
Journaljournal of the physical society of japan
Issue number11
Publication statusPublished - 2006 Nov


  • (CuBr)LaNbO
  • Collinear order
  • Frustration
  • Ion exchange
  • J-J model
  • Square lattice

ASJC Scopus subject areas

  • Physics and Astronomy(all)


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