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arXiv 0801.4875cond-mat.str-el
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Yb $_{2}$ Pt $_{2}$ Pb:Shastry-Sutherland晶格中的磁阻挫

Yb$_{2}$Pt$_{2}$Pb: Magnetic frustration in the Shastry-Sutherland lattice

M. S. Kim, M. C. Bennett, M. C. Aronson

摘要:

我们已经合成了Yb $_{2}$ Pt $_{2}$ Pb的单晶,其在层状U $_{2}$ Pt $_{2}$ Sn型结构中结晶,其中Yb离子的平面位于三角形网络上。我们在这里报告的磁化强度,比热,电阻率实验的第一个结果。晶格常数和高温磁化率表明Yb离子是三价的,而比热中的肖特基峰表明其基态是一个隔离良好的双峰。观察到显着的磁各向异性,垂直和平行于磁平面的磁化率的比例不同,在最低温度下高达30倍。反铁磁序发生在Néel温度$T_{\rm N}$ =2.07 K,转变温度是超过一个数量级小于平均场相互作用所反映的面内外斯温度。在磁化率和电阻率中发现了短程磁波动的进一步证据,它们在$T_{\rm N}$以上具有宽峰,并且在$T_{\rm N}$处磁熵的缓慢发展中发现了短程磁波动的进一步证据。我们的实验表明Yb $_{2}$ Pt $_{2}$ Pb是一个准二维的局域磁矩系统,其中强的磁阻挫可能来自于下面的Shastry-Sutherland晶格的几何结构.

英文摘要:

We have synthesized single crystals of Yb$_{2}$Pt$_{2}$Pb, which crystallize in the layered U$_{2}$Pt$_{2}$Sn-type structure, where planes of Yb ions lie on a triangular network. We report here the first results of magnetization, specific heat, and electrical resistivity experiments. The lattice constants and high temperature magnetic susceptibility indicate that the Yb ions are trivalent, while Schottky peaks in the specific heat show that the ground state is a well isolated doublet. Significant magnetic anisotropy is observed, with the ratio of susceptibilities perpendicular and parallel to the magnetic planes differing by as much as a factor of 30 at the lowest temperatures. Antiferromagnetic order occurs at a Néel temperature $T_{\rm N}$=2.07 K, a transition temperature which is more than an order of magnitude smaller than the mean field interactions reflected by the in-plane Weiss temperature. Further evidence for short ranged magnetic fluctuations is found in the magnetic susceptibility and electrical resistivity, which have broad peaks above $T_{\rm N}$, and in the slow development of the magnetic entropy at $T_{\rm N}$. Our experiments indicate that Yb$_{2}$Pt$_{2}$Pb is a quasi-two dimensional and localized moment system, where strong magnetic frustration may arise from the geometry of the underlying Shastry-Sutherland lattice.

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