Theoretical studies, based on three independent techniques, of the band structure of a one-dimensional width-modulated magnonic crystal under a transverse magnetic field are reported. The band diagram is found to display distinct behaviors when the transverse field is either larger or smaller than a critical value. The widths and center positions of bandgaps exhibit unusual non-monotonic and large field-tunability through tilting the direction of magnetization. Some bandgaps can be dynamically switched on and off by simply tuning the strength of such a static field. Finally, the impact of the lowered symmetry of the magnetic ground state on the spin-wave excitation efficiency of an oscillating magnetic field is discussed. Our finding reveals that the magnetization direction plays an important role in tailoring magnonic band structures and hence in the design of dynamic spin-wave switches.
Spin waves in alloys at finite temperatures: application for FeCo magnonic crystal
从理论上研究了温度和无序度对磁振子晶体Fe $_{1-c}$ Co $_{c}$自旋波谱的影响。我们的形式主义是基于分析的海森堡哈密顿的波矢量和频率依赖的横向磁化率的装置。进入模型的交换积分由\emph{ab initio}磁力定理得到。为了解释有限温度下磁振子谱的软化，我们采用相干势近似处理无序和无规相近似。该合金在自旋电子学应用中表现出许多有利的特性。除了高居里温度外，它的磁振子带隙在高温下保持稳定，并且在很大程度上不受无序的影响。我们特别注意合金化引入的磁振子的衰减。阻尼原来是一个非单调的函数的杂质浓度，由于非平凡的演变的交换积分的值与Co浓度。磁振子的无序诱导阻尼估计比它们的朗道阻尼小得多。
Electromagnon excitations in modulated multiferroics
螺旋磁体铁电性的唯象理论[M. Mostovich，Phys. Rev. Lett. 96，067601（2006）]被概括为描述具有均匀铁电极化和空间调制铁电极化的一致状态。本说明书中的关键点是磁电耦合的对称部分，因为尽管与均匀分量无关，但它对极化的非均匀部分起着重要作用。我们在调制磁系统的一般例子中说明了这一重要性：纵向和横向自旋密度波状态和平面摆线相位。我们发现，即使在没有均匀铁电性的情况下，极化关联函数遵循系统的软磁行为，由于磁电效应。我们的结果可以很容易地推广到更复杂类型的磁有序，并且应用可能涉及凝聚态物理中的各种自然和人工系统（例如，可以从动态介电响应测量中提取磁振子特性）。
Magnetic field induced modulation of heat transport in CrPS$_4$ probed by TaIrTe$_4$ transverse Seebeck thermometry
University of Groningen（格罗宁根大学）；Cavendish Laboratory, University of Cambridge（剑桥大学卡文迪许实验室）；School of Physics and Astronomy, University of Leeds（利兹大学物理与天文学院）
