Plasma-Like Negative Capacitance in Nano-Colloids
  A negative capacitance has been observed in a nano-colloid between 0.1 and 10^-5 Hz. The response is linear over a broad range of conditions. The low-omega dispersions of both the resistance and capacitance are consistent with the free-carrier plasma model, while the transient behavior demonstrates an unusual energy storage mechanism. A collective excitation, therefore, is suggested. 
J. Shulman (1), S. Tsui (1), F. Chen (1), Y. Y. Xue (1), C. W. Chu (1   and 2 and 3) ((1) Department of Physics and TCSUH, U...