We demonstrate the integration of a mesoscopic ferromagnetic needle with acavity optomechanical torsional resonator, and its use for quantitativedetermination of the needle's magnetic properties, as well as amplification andcooling of the resonator motion. With this system we measure torques as smallas 32 zNm, corresponding to sensing an external magnetic field of 0.12 A/m (150nT). Furthermore, we are able to extract the magnetization (1710 kA/m) of themagnetic sample, not known a priori, demonstrating this system's potential forstudies of nanomagnetism. Finally, we show that we can magnetically drive thetorsional resonator into regenerative oscillations, and dampen its mechanicalmode temperature from room temperature to 11.6 K, without sacrificing torquesensitivity.
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机译：我们演示了介观铁磁针与腔光学机械扭转共振器的集成，以及其用于定量确定针的磁性以及共振器运动的放大和冷却的用途。使用该系统，我们测量的扭矩小至32 zNm，对应于感应到0.12 A / m（150nT）的外部磁场。此外，我们能够提取先验未知的磁性样品的磁化强度（1710 kA / m），这证明了该系统对纳米磁性的潜在研究。最后，我们证明了在不牺牲扭矩灵敏度的前提下，我们可以将扭转共振器磁化为再生振荡，并将其机械模式温度从室温降低到11.6K。
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