Plasmalike negative capacitance in nanocolloids

A negative capacitance has been observed in a nanocolloid between 0.1 and 10−5 Hz. The response is linear over a broad range of conditions. The low-␻ dispersions of both the resistance and capacitance are consistent with the free-carrier plasma model, while the transient behavior demonstrates a possible energy storage mechanism. A collective excitation, therefore, is suggested. © 2007 American Institute of Physics. ͓DOI: 10.1063/1.2431782͔