Kyle Willick: Carbon Nanotube Mechanical Resonators - Magnetic force detection and fast sensing
Suspended carbon nanotube (CNT) resonators have demonstrated excellent sensitivity in mass and force sensing applications to date. I will introduce these mechanical resonators, and how they can be combined with magnetic field gradients to realize magnetic moment readout. Euler-Bernoulli beam modelling of the CNT indicates that single electron spin flip detection on timescales of 10 microseconds is possible, which would allow measurement of molecular nanomagnet states within their spin relaxation timescales. However, the measurement times for CNT devices in cryogenic setups is usually limited by the CNT contact resistance and parasitic capacitances of the system. I will describe an experiment using a cold heterojunction bipolar transistor amplifying circuit near the CNT to measure the mechanical amplitude of the resonator on microsecond timescales. This circuit was used to resolve transient behaviour of the CNT, including the response to driving into the strongly non-linear regime.