Why spin ice obeys the ice rules
Why spin ice obeys the ice rules
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DOI：
10.1103/physrevlett.95.217201
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发表时间：
2005-11-18
影响因子：
8.6
通讯作者：
Sondhi, SL
中科院分区：
文献类型：
--
作者：
Isakov, SV;Moessner, R;Sondhi, SL
自旋冰化合物（例如 Ho2Ti2O7 和 Dy2Ti2O7）的低温熵可以通过烧绿石晶格上的最近邻反铁磁伊辛模型（即“冰规则”）很好地描述。这是令人惊讶的，因为自旋之间的主要耦合是它们的长程偶极子相互作用。我们表明，这种现象可以相当优雅地理解：可以通过添加较短范围的项来构造偶极子相互作用模型，这会产生完全相同的基态，因此 T = 0 熵，作为最近邻相互作用。对模型和真实偶极相互作用之间微小差异的处理再现了 Gingras 等人的数值工作。详细。我们还得出了交互之间的投影等价的更普遍的概念。
The low-temperature entropy of the spin ice compounds, such as Ho2Ti2O7 and Dy2Ti2O7, is well described by the nearest-neighbor antiferromagnetic Ising model on the pyrochlore lattice, i.e., by the "ice rules." This is surprising since the dominant coupling between the spins is their long ranged dipole interaction. We show that this phenomenon can be understood rather elegantly: one can construct a model dipole interaction, by adding terms of shorter range, which yields precisely the same ground states, and hence T = 0 entropy, as the nearest-neighbor interaction. A treatment of the small difference between the model and true dipole interactions reproduces the numerical work by Gingras et al. in detail. We are also led to a more general concept of projective equivalence between interactions.