二次元三角格子上で実現したスピンの無秩序な量子状態  [in Japanese] Spin Disordered State in a Two-Dimensional Triangular Antiferromagnet  [in Japanese]

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Author(s)

Abstract

従来型の磁気秩序を抑えることで現れる新奇な状態への興味から,幾何学的フラストレーションを持つ系が近年注目を集めている.その中で最も基本的な三角格子反強磁性体はこれまで盛んに研究されてきたが,そのほとんどは三次元性を通じて低温で120度低温で120度構造に代表される磁気的長距離秩序を示す.そうした中,最近我々は層状カルコゲナイド化合物NiGa_2S_4が極めて二次元性の高い反強磁性相関を持つS=1の三角格子スピン系であることを発見した.興味深いことに,この物質は低温まで反強磁性の長距離秩序を示さず,代わりに何らかのコヒーレンスを持つスピン無秩序状態が現れることが分かってきた.本概説ではこのNiGa_2S_4とその不純物効果の実験結果について紹介する.

Geometrically frustrated magnets have attracted interest because of their possible novel phenomena upon suppression of conventional magnetic orders. Among such magnets, one of the simplest examples, the triangular antiferromagnet, has been studied extensively. However, most of the systems have been found to order antiferromagnetically at low temperatures. Recently, we have developed NiGa_2S_4, as the first example of a bulk low spin (S≤1) 2D antiferromagnet with an exact triangular lattice. This compound exhibits a spin disordered state instead of either antiferromagnetic order or conventional spin glass state. In this review, we present our recent experimental results for NiGa_2S_4 and its nonmagnetic impurity effects, as well as the relevant theoretical results.

Journal

  • Butsuri

    Butsuri 62(4), 254-259, 2007-04-05

    The Physical Society of Japan (JPS)

References:  18

Codes

  • NII Article ID (NAID)
    110006242014
  • NII NACSIS-CAT ID (NCID)
    AN00196952
  • Text Lang
    JPN
  • Article Type
    REV
  • ISSN
    00290181
  • NDL Article ID
    8696781
  • NDL Source Classification
    ZM35(科学技術--物理学)
  • NDL Call No.
    Z15-13
  • Data Source
    CJP  NDL  NII-ELS 
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