论文标题
一般应用的磁场中的自旋冰：Kasteleyn过渡，磁性扭矩和旋转磁平衡效应
Spin ice in a general applied magnetic field: Kasteleyn transition, magnetic torque and rotational magnetocaloric effect
论文作者
论文摘要
自旋冰是一种范式沮丧的系统，以磁性单极的出现和低温下的磁性熵而闻名。由于旋转冰熵与Zeeman能量之间的竞争，它在存在外部磁场的情况下表现出异常的行为。对此的研究通常集中在沿高对称方向应用的田地上：[111]，[001]和[110]。在这里，我们考虑了沿任意方向的外部场的自旋冰模型。我们发现，以$ [001] $字段而闻名的Kasteleyn过渡也出现在通用场方向上，并计算关联的Kasteleyn温度$ t_k $作为场方向的函数。 $ t_k $消失了，对数依赖于场角，接近某些特殊野外方向。我们进一步研究了使用Husimi Cactus近似，以$ t> t_k $以旋转冰的热力学特性。由于系统将其冷却到$ t_k $时出现大型磁性扭矩，因此倾向于将$ [001] $ Crystal轴与外部场对齐。该模型还表现出旋转磁量的效应：通过对固定场相对于固定场旋转晶体可以通过旋转晶体来获得明显的温度变化。
Spin ice is a paradigmatic frustrated system famous for the emergence of magnetic monopoles and a large magnetic entropy at low temperatures. It exhibits unusual behavior in the presence of an external magnetic field as a result of the competition between the spin ice entropy and the Zeeman energy. Studies of this have generally focused on fields applied along high symmetry directions: [111], [001], and [110]. Here we consider a model of spin ice with external field in an arbitrary direction. We find that the Kasteleyn transition known for $[001]$ fields, appears also for general field directions and calculate the associated Kasteleyn temperature $T_K$ as a function of field direction. $T_K$ is found to vanish, with a logarithmic dependence on field angle, approaching certain lines of special field directions. We further investigate the thermodynamic properties of spin ice for $T>T_K$, using a Husimi cactus approximation. As the system is cooled towards $T_K$ a large magnetic torque appears, tending to align the $[001]$ crystal axis with the external field. The model also exhibits a rotational magnetocaloric effect: significant temperature changes can be obtained by adabiatically rotating the crystal relative to a fixed field.
