Temperature Dependence of Magnetic Excitations: Terahertz Magnons above the Curie Temperature.
Temperature Dependence of Magnetic Excitations: Terahertz Magnons above the Curie Temperature.
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磁激发的温度依赖性：高于居里温度的太赫兹磁振子
DOI：
10.1103/physrevlett.118.127203
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发表时间：
2017
影响因子：
8.6
通讯作者：
J. Kirschner
中科院分区：
文献类型：
--
作者：
H. J. Qin;Kh. Zakeri;A. Ernst;J. Kirschner
当给定维度的有序自旋系统经历二阶相变时，有序参数（即磁化强度对温度的依赖性）可以通过基本集体自旋激发（磁振子）的热激发来很好地描述。然而，磁振子本身的行为作为温度和跨转变温度的函数，是一个未知的问题。利用自旋极化高分辨率电子能量损失光谱，我们监测在超薄铁磁体中激发的高能（太赫兹）磁振子随温度的变化。我们发现磁振子的能量和寿命随着温度的升高而降低。温度引起的磁振子能量和寿命的重整化取决于波矢量。我们提供了温度引起的阻尼的定量结果，并讨论了可能的机制，例如多磁振子散射。对决定磁振子传播的物理量的仔细研究表明，即使在远高于此的温度下，太赫兹磁振子也能维持其传播特性。
When an ordered spin system of a given dimensionality undergoes a second order phase transition, the dependence of the order parameter, i.e., magnetization on temperature, can be well described by thermal excitations of elementary collective spin excitations (magnons). However, the behavior of magnons themselves, as a function of temperature and across the transition temperature, is an unknown issue. Utilizing spin-polarized high resolution electron energy loss spectroscopy, we monitor the high-energy (terahertz) magnons, excited in an ultrathin ferromagnet, as a function of temperature. We show that the magnons’ energy and lifetime decrease with temperature. The temperature-induced renormalization of the magnons’ energy and lifetime depends on the wave vector. We provide quantitative results on the temperature-induced damping and discuss the possible mechanism, e.g., multimagnon scattering. A careful investigation of physical quantities determining the magnons’ propagation indicates that terahertz magnons sustain their propagating character even at temperatures far above.
通过自旋极化电子探测磁振子
影响因子：
3.7
作者：
K. Zakeri;J. Kirschner
通讯作者：
J. Kirschner