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arXiv 0704.3869cond-mat.str-el
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自旋圆环Mo_{75} V_{20}交换相互作用的评价

Evaluation of Exchange Interactions of the Spin Doughnut Mo_{75}V_{20}

S. Takemura, Y. Fukumoto

摘要:

利用有限温度Lanczos方法研究了自旋甜甜圈Mo_{75} V_{20}的磁性,它是一个具有20个自旋的受抑磁性团簇.我们的模型哈密顿量由一个十自旋环和两个五自旋环组成,它们具有最近邻反铁磁耦合J和J”。五自旋环通过反铁磁交换相互作用J'耦合到十自旋环,从而形成一个J键和两个J'键的等腰三角形。将理论磁化率与Muller等人测量的实验磁化率拟合,交换参数J=388 K,J '= 163 K,J”=81 K。这个系统最有趣的特点是,尽管J '> J”,但两个五自旋环在低温下表现得像两个自由自旋。我们还计算了比热随温度的变化关系,发现在T_sim J,J ″和J ′/100处有三个峰。

英文摘要:

Magnetic properties of the spin doughnut Mo_{75}V_{20}, which is a frustrated magnetic cluster with twenty spins, are studied by using the finite-temperature Lanczos method. Our model Hamiltonian consists of one ten-spin ring and two five-spin rings with nearest-neighbor antiferromagnetic couplings J and J". The five-spin rings are coupled to the ten-spin ring by an antiferromagnetic exchange interaction J' so as to form isosceles triangles of one J-bond and two J'-bonds. Fitting the theoretical magnetic susceptibility with the experimental one measured by Muller et al., the exchange parameters are estimated as J=388 K, J'=163 K and J"=81 K. The most interesting feature of this system is that the two five-spin rings behave like two free-spins at low temperatures in despite of J'>J". We also calculate temperature dependence of the specific heat, and find three peaks at T sim J, J" and J'/100.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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