Dissipation in nanocrystalline-diamond nanomechanical resonators

We have measured the dissipation and frequency of nanocrystalline-diamond nanomechanical resonators with resonant frequencies between 13.7 MHz and 157.3 MHz, over a temperature range of 1.4-274 K. Using both magnetomotive network analysis and a time-domain ring-down technique, we have found the dissipation in this material to have a temperature dependence roughly following T-0.2, with Q(-1)approximate to10(-4) at low temperatures. The frequency dependence of a large dissipation feature at similar to35-55 K is consistent with thermal activation over a 0.02 eV barrier with an attempt frequency of 10 GHz. (C) 2004 American Institute of Physics.