论文标题
磁性单极放松效果在旋转冰$ _2 $ ti $ _2 $ o $ _7 $
Magnetic monopole relaxation effects in spin ice Dy$_2$Ti$_2$O$_7$
论文作者
论文摘要
自旋冰化合物可以探索凝聚态物质系统中磁性的动力学。在这项研究中，我们使用交流量热法来探测经典旋转冰层化合物的热容量的动态响应dy $ _2 $ _2 $ _2 $ _2 $ o $ $ _7 $在低温（0.5-5 K）。使用0.01-500 Hz的频率，我们发现在测得的热容量中具有强频率依赖性，并且能够研究对相应时间尺度的热弛豫效应。放松时间$τ$取决于热容量的频率依赖性，作为热容量饱和的特征频率。提取的$τ$显示出低于1 K的发散行为，达到$ \ sim $ 6 s 0.65 K，类似于以前的研究中看到的放松时间。相应的比热显示在该温度周围的最大值。进行动态的蒙特卡洛模拟，我们验证了特定的热频率响应的起源是在慢速磁性冰冰的慢速磁单电极动力学中。与其他技术在先前的研究中提到的2.5 ms相比，我们发现每个蒙特卡洛步骤的时间尺度为20 ms。
Spin ice compounds enable the exploration of the dynamics of magnetic monopoles in condensed matter systems. In this study, we use ac calorimetry to probe the dynamical response of the heat capacity of the classical spin-ice compounds Dy$_2$Ti$_2$O$_7$ at low temperatures (0.5-5 K). Using frequencies of 0.01-500 Hz, we find a strong frequency dependence in the measured heat capacity and are able to study thermal relaxation effects on the corresponding timescales. The relaxation time $τ$ is determined from the frequency dependence of the heat capacity as the characteristic frequency below which the heat capacity saturates. The extracted $τ$ shows a divergent behavior below 1 K reaching $\sim$6 s at 0.65 K, similar to the relaxation time seen in previous studies. Corresponding specific heat shows a maximum around this temperature. Performing dynamic Monte Carlo simulations, we verify that the specific heat frequency response has its origin in the slow magnetic monopole dynamics indigenous to spin ice. We find a timescale of 20 ms per Monte Carlo step at 4 K in contrast to 2.5 ms mentioned in previous studies by other techniques.
