Ferromagnetic gyroscopes for tests of fundamental physics
Ferromagnetic gyroscopes for tests of fundamental physics
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DOI：
10.1088/2058-9565/abd892
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发表时间：
2021-04-01
影响因子：
6.7
通讯作者：
Kimball, Derek F. Jackson
中科院分区：
文献类型：
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作者：
Fadeev, Pavel;Timberlake, Chris;Kimball, Derek F. Jackson
铁磁陀螺仪（FG）是一种铁磁体，其角动量由电子自旋极化主导，并且将在外部扭矩（例如由于磁场）的作用下进行。在这里，我们建模和分析FG的动态和灵敏度，侧重于实验实现的实际方案。在一个自由浮动的FG的情况下，我们模型的过渡动力学为主的天平动在相对较高的外部施加的磁场，在相对较低的施加的磁场的进动为主。天平动频率的测量使得能够原位确定磁场和将场降低到阈值以下的技术，对于该阈值，进动主导FG动态。我们注意到，陀螺行为的证据是目前，即使在磁场远大于阈值以下的进动占主导地位的领域。我们还通过迈斯纳效应模拟了浮在I型超导体上方的FG的动态，发现对于尺寸大于约100 nm的FG，所观察到的进动频率与自由浮动的FG相比有所降低。这是由于类似于负反馈的效应，该负反馈由超导体对FG的场的扭曲引起。最后，我们评估的敏感性的FG悬浮在I型超导体上的异国情调的自旋相关的相互作用在实际的实验条件下，展示了潜在的FG的基础物理测试。
A ferromagnetic gyroscope (FG) is a ferromagnet whose angular momentum is dominated by electron spin polarization and that will process under the action of an external torque, such as that due to a magnetic field. Here we model and analyze FG dynamics and sensitivity, focusing on practical schemes for experimental realization. In the case of a freely floating FG, we model the transition from dynamics dominated by libration in relatively high externally applied magnetic fields, to those dominated by precession at relatively low applied fields. Measurement of the libration frequency enables in situ determination of the magnetic field and a technique to reduce the field below the threshold for which precession dominates the FG dynamics. We note that evidence of gyroscopic behavior is present even at magnetic fields much larger than the threshold field below which precession dominates. We also model the dynamics of an FG levitated above a type-I superconductor via the Meissner effect, and find that for FGs with dimensions larger than about 100 nm the observed precession frequency is reduced compared to that of a freely floating FG. This is due to an effect akin to negative feedback that arises from the distortion of the field from the FG by the superconductor. Finally we assess the sensitivity of an FG levitated above a type-I superconductor to exotic spin-dependent interactions under practical experimental conditions, demonstrating the potential of FGs for tests of fundamental physics.