Divinskiy B, Merbouche H, Demidov V E, Nikolaev K O, Soumah L, Gouéré D, Lebrun R, Cros V, Youssef Jamal Ben, Bortolotti P, Anane A, Demokritov S O
Institute for Applied Physics, University of Muenster, Corrensstrasse 2-4, 48149, Muenster, Germany.
Unité Mixte de Physique, CNRS, Thales, Université Paris-Saclay, 91767, Palaiseau, France.
Nat Commun. 2021 Nov 11;12(1):6541. doi: 10.1038/s41467-021-26790-y.
The quanta of magnetic excitations - magnons - are known for their unique ability to undergo Bose-Einstein condensation at room temperature. This fascinating phenomenon reveals itself as a spontaneous formation of a coherent state under the influence of incoherent stimuli. Spin currents have been predicted to offer electronic control of Bose-Einstein condensates, but this phenomenon has not been experimentally evidenced up to now. Here we show that current-driven Bose-Einstein condensation can be achieved in nanometer-thick films of magnetic insulators with tailored nonlinearities and minimized magnon interactions. We demonstrate that, above a certain threshold, magnons injected by the spin current overpopulate the lowest-energy level forming a highly coherent spatially extended state. We quantify the chemical potential of the driven magnon gas and show that, at the critical current, it reaches the energy of the lowest magnon level. Our results pave the way for implementation of integrated microscopic quantum magnonic and spintronic devices.
磁激发的量子——磁振子——以其在室温下发生玻色-爱因斯坦凝聚的独特能力而闻名。这一迷人的现象表现为在非相干刺激的影响下自发形成一种相干态。自旋电流被预测可实现对玻色-爱因斯坦凝聚体的电子控制，但到目前为止，这一现象尚未得到实验证实。在此，我们表明，通过具有定制非线性和最小化磁振子相互作用的磁性绝缘体纳米厚膜，可以实现电流驱动的玻色-爱因斯坦凝聚。我们证明，在某个阈值以上，由自旋电流注入的磁振子使最低能量级的粒子数过多，从而形成高度相干的空间扩展态。我们对驱动磁振子气体的化学势进行了量化，并表明在临界电流下，它达到最低磁振子能级的能量。我们的结果为集成微观量子磁振子和自旋电子器件的实现铺平了道路。
