The possibility of experimental observation of the ultrasonic attenuation in the ferromagnet $\mathrm{LuCo}{}_3$ near the low-spin-high-spin crossover is discussed. We show that ultrasound propagation gives rise to transitions between states of the magnon band due to absorption of phonons, and this process is highly sensitive to the value of magnetization. The high magnetic field, which governs the crossover, alters the ultrasound propagation regime from off-resonant to resonant and we formulate a criterion of the change. Calculated temperature and field dependences of the ultrasonic wave number and attenuation clearly demonstrate anomalies in these characteristics in the vicinity of the crossover at intermediate temperatures far below the Curie temperature.

中文翻译：

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LuCo3中低自旋-高自旋交叉点附近的超声传播理论

实验观察铁磁体中超声波衰减的可能性$\mathrm{卢科}{}_3$讨论了低自旋-高自旋交叉附近。我们表明，由于声子的吸收，超声传播引起了磁子带状态之间的跃迁，并且该过程对磁化值高度敏感。控制交叉的高磁场将超声传播状态从非共振改变为共振，我们制定了变化的标准。超声波数和衰减的计算温度和场依赖性清楚地表明，在远低于居里温度的中间温度下，这些特性在交叉附近的异常。