Crystal shape-dependent magnetic susceptibility and Curie law crossover in the spin ices Dy2Ti2O7 and Ho2Ti2O7
Crystal shape-dependent magnetic susceptibility and Curie law crossover in the spin ices Dy2Ti2O7 and Ho2Ti2O7
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DOI：
10.1088/0953-8984/25/38/386002
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发表时间：
2013-09-25
影响因子：
2.7
通讯作者：
Bramwell, S. T.
中科院分区：
文献类型：
--
作者：
Bovo, L.;Jaubert, L. D. C.;Bramwell, S. T.
本文报道了自旋冰材料Dy_2Ti_2O_7和Ho_2Ti_2O_7在1.8-300 K温度范围内等温磁化率的实验测定。球形晶体的使用允许精确校正退磁场，并允许估计真实的体等温磁化率（chi T）（T）。这已被比较对基于Husimi树近似的自旋冰模型的理论表达式。在T > 10 K时，实验与理论之间的一致性非常好，但在低于该温度时会出现系统偏差。我们的研究结果在很大程度上解决了中子散射和散装测量之间的明显分歧，已经注意到。他们还表明，在自旋冰的磁化研究中使用非球形晶体可能会引入非常显着的系统误差，虽然我们注意到一些有趣的，可能是新的系统学有关的立方体样品的退磁因子。最后，我们的研究结果表明，如何实验磁化率测量自旋冰可用于提取系统的特征能量尺度和相应的化学势紧急磁单极子。
We present an experimental determination of the isothermal magnetic susceptibility of the spin ice materials Dy2Ti2O7 and Ho2Ti2O7 in the temperature range 1.8-300 K. The use of spherical crystals has allowed accurate correction for demagnetizing fields and allowed the true bulk isothermal susceptibility (chi T)(T) to be estimated. This has been compared against a theoretical expression based on a Husimi tree approximation to the spin ice model. Agreement between experiment and theory is excellent at T > 10 K, but systematic deviations occur below that temperature. Our results largely resolve an apparent disagreement between neutron scattering and bulk measurements that has been previously noted. They also show that the use of non-spherical crystals in magnetization studies of spin ice may introduce very significant systematic errors, although we note some interesting-and possibly new-systematics concerning the demagnetizing factor in cuboidal samples. Finally, our results show how experimental susceptibility measurements on spin ices may be used to extract the characteristic energy scale of the system and the corresponding chemical potential for emergent magnetic monopoles.