Spin dynamics in the high-field phases of volborthite
Spin dynamics in the high-field phases of volborthite
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伏硼铁矿高场相的自旋动力学
DOI：
10.1103/physrevb.96.180413
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发表时间：
2017
影响因子：
3.7
通讯作者：
Z. Hiroi
中科院分区：
文献类型：
--
作者：
M. Yoshida;K. Nawa;H. Ishikawa;M. Takigawa;M. Jeong;S. Kramer;M. Horvatic;C. Berthier;K. Matsui;T. Goto;S. Kimura;T. Sasaki;J. Yamaura;H. Yoshida;Y. Okamoto;Z. Hiroi
我们报告的单晶NMR研究volborthite，这被认为是一个准二维阻挫磁铁与竞争的铁磁和反铁磁相互作用。在28T以上的1/3磁化平台区，核自旋-晶格弛豫率表明存在一个激发能隙，其有效因子在4.6 - 5.9之间，指向磁振子束缚态。在26 T以下，差距已经闭合，NMR谱表明具有高斯样分布的小内场，其中在顺磁状态下显示出幂律样的温度依赖性，这类似于与磁序相关的自旋波动的减慢。我们讨论了一个奇异的自旋态的可能性所造成的磁振子束缚态的凝聚低于磁化平台。
We report single-crystalNMR studies on volborthite, which is regarded as a quasi-two-dimensional frustrated magnet with competing ferromagnetic and antiferromagnetic interactions. In the 1/3 magnetization plateau above 28 T, the nuclear spin-lattice relaxation rateindicates an excitation gap with a large effectivefactor in the range of 4.6–5.9, pointing to magnon bound states. Below 26 T where the gap has closed, the NMR spectra indicate small internal fields with a Gaussian-like distribution, whereasshows a power-law-like temperature dependence in the paramagnetic state, which resembles a slowing down of spin fluctuations associated with magnetic order. We discuss the possibility of an exotic spin state caused by the condensation of magnon bound states below the magnetization plateau.