LETTER TO THE EDITOR: Low temperature magnetic properties of frustrated pyrochlore ferromagnets Ho2Sn2O7 and Ho2Ti2O7
LETTER TO THE EDITOR: Low temperature magnetic properties of frustrated pyrochlore ferromagnets Ho2Sn2O7 and Ho2Ti2O7
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致编辑的信：受挫烧绿石铁磁体 Ho2Sn2O7 和 Ho2Ti2O7 的低温磁性能
DOI：
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发表时间：
2000
期刊：
影响因子：
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通讯作者：
T. Sakakibara
中科院分区：
文献类型：
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作者：
K. Matsuhira;Y. Hinatsu;K. Tenya;T. Sakakibara
交流和直流磁化率已被测量的挫折烧绿石铁磁体Ho_2Sn_2O_7和Ho_2Ti_2O_7在温度下降到100 mK。在交流磁化率中，在约1 K处观察到χ'（同相分量）的急剧下降和单个最大值的χ“（正交分量）。这些峰位的频率依赖性表明，在低温下存在缓慢的磁弛豫，其弛豫时间服从Arrhenius公式，其中Ho 2Sn 2 O 7和Ho 2 Ti 2 O 7的势垒分别为Eb = 19.6 K和27.5 K。Ho 2Sn 2 O 7的直流磁化强度在Tp~ 0.75 K以下的1 kOe处随温度的变化具有很强的不可逆性，零场冷却（ZFC）曲线在Tp处出现一个非常尖锐的峰，而场冷却曲线在Tp处没有异常，并随T的降低而单调增加.在直流磁化过程中的ZFC状态在0.46 K，急剧增加的时刻发生在2 kOe以上，和不可逆性消失在约15 kOe的时刻铁磁饱和。这些结果表明，聚集的磁矩的大小是几个四面体的顺序，与最近提出的“自旋冰”模型。
AC and DC magnetic susceptibilities have been measured on frustrated pyrochlore ferromagnets Ho2Sn2O7 and Ho2Ti2O7 at temperatures down to 100 mK. In the AC magnetic susceptibility, a dramatic drop of χ' (in-phase component) and a single maximum of χ'' (quadrature component) are observed at around 1 K. The frequency dependence of these peak positions indicates the presence of a slow magnetic relaxation at low temperature, whose relaxation time obeys the Arrhenius formula with the energy barrier Eb = 19.6 K and 27.5 K for Ho2Sn2O7 and Ho2Ti2O7, respectively. Strong irreversibility is also observed in the temperature dependence of the DC magnetization of Ho2Sn2O7 at 1 kOe below Tp~ 0.75 K; the zero-field-cooling (ZFC) curve indicates a very sharp peak at Tp, whereas the field-cooling curve has no anomaly at Tp and increases monotonically with decreasing T. In the DC magnetization process of the ZFC state at 0.46 K, a steep increase of the moment occurs above 2 kOe, and the irreversibility disappears at around ~15 kOe where the moment ferromagnetically saturates. These results indicate a clustering of magnetic moment whose size is of the order of a few tetrahedra, consistent with a recently proposed `spin ice' model.