KMnF3热性能的临界行为
Critical behaviour of the thermal properties of KMnF3
摘要：
利用交流热电量热计同时测量了KMnF 3反铁磁-顺磁相变前后的比热、热导率和热扩散率。发现热扩散率的临界指数和幅值比与比热的临界指数和幅值比相同。这两个值都与各向同性磁体的三维海森堡模型的预测一致，尽管这种转变不仅是磁性的，而且也是结构性的。的热导率示出了一个宽的峰值在尼尔温度，这可能与减少的声子散射的自旋波动的转变温度接近。
英文摘要：
An ac photopyroelectric calorimeter has been used to simultaneously measure the specific heat, thermal conductivity, and thermal diffusivity around the antiferromagnetic to paramagnetic phase transition in KMnF3. It has been found that the critical exponent and the amplitude ratio of the thermal diffusivity are the same as those of the specific heat. Both values agree with the predictions of the three-dimensional Heisenberg model for isotropic magnets, although this transition is not only magnetic but also structural as well. The thermal conductivity shows a broad peak at the Neel temperature that could be related to a reduction of the phonon scattering by the spin fluctuation as the transition temperature is approached.
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