Knyazev G A, Kuzmichev A N, Petrov P E, Savochkin I V, Vetoshko P M, Belotelov V I, Bunkov Yu M
Opt Express. 2024 Apr 8;32(8):13761-13768. doi: 10.1364/OE.513923.
Bose-Einstein condensation occurs at an appropriate density of bosonic particles, depending on their mass and temperature. The transition from the semiclassical paradigm of spin waves to the magnon Bose-Einstein condensed state (mBEC) was obtained experimentally with increasing magnon density. We used the Faraday rotation effect to study the spatial distribution of the magnon density and phase far from their excitation region. A coherent magnetization precession was observed throughout the sample, which indicates the formation of a magnon BEC. It is shown that this result under experimental conditions goes beyond the applicability of the Landau-Lifshitz-Gilbert semiclassical theory.
玻色-爱因斯坦凝聚在玻色子粒子的适当密度下发生，这取决于它们的质量和温度。随着磁振子密度的增加，实验上实现了从自旋波的半经典范式到磁振子玻色-爱因斯坦凝聚态（mBEC）的转变。我们利用法拉第旋转效应研究了远离其激发区域的磁振子密度和相位的空间分布。在整个样品中观察到了相干磁化进动，这表明形成了磁振子玻色-爱因斯坦凝聚。结果表明，在实验条件下，这一结果超出了朗道-栗弗席兹-吉尔伯特半经典理论的适用范围。
