Department of Physics and Astronomy, University of California , Riverside, California 92521, United States , and.
Nano Lett. 2014 Jun 11;14(6):2982-7. doi: 10.1021/nl403936a. Epub 2014 May 8.
We measure the quality factor Q of electrically driven few-layer graphene drumhead resonators, providing an experimental demonstration that Q ∼ 1/T, where T is the temperature. We develop a model that includes intermodal coupling and tensioned graphene resonators. Because the resonators are atomically thin, out-of-plane fluctuations are large. As a result, Q is mainly determined by stochastic frequency broadening rather than frictional damping, in analogy to nuclear magnetic resonance. This model is in good agreement with experiment. Additionally, at larger drives the resonance line width is enhanced by nonlinear damping, in qualitative agreement with recent theory of damping by radiation of in-plane phonons. Parametric amplification produced by periodic thermal expansion from the ac drive voltage yields an anomalously large line width at the largest drives. Our results contribute toward a general framework for understanding the mechanisms of dissipation and spectral line broadening in atomically thin membrane resonators.
我们测量了电驱动少层石墨烯鼓面谐振器的品质因数 Q，实验证明 Q∼1/T，其中 T 是温度。我们开发了一个包含模态耦合和张紧石墨烯谐振器的模型。由于谐振器是原子级薄的，因此面外波动较大。结果，Q 主要由随机频率展宽决定，而不是摩擦阻尼，类似于核磁共振。该模型与实验吻合较好。此外，在较大的驱动下，共振线宽会被非线性阻尼增强，这与最近关于面内声子辐射阻尼的理论定性一致。周期性热膨胀引起的交流驱动电压产生的参量放大在最大驱动下导致线宽异常增大。我们的结果有助于建立一个理解原子薄膜谐振器中耗散和光谱线展宽机制的通用框架。
