Anomalous capacitance and limit cycle in Kondo insulators.

摘要

Kondo insulators are strongly correlated electronic system containing rare-earth or actinide elements, and the Fermi energy lies in the middle of very small excitation gap opened by Kondo effect. The main focus on these materials has been on understanding of the gap opened by the many body effect of the dense kondo lattice without magnetic transition. First, we studies memristor behavior in a macroscopic bulk Kondo insulator Ce3Bi 4Pt3. The characteristic ac current and voltage relation of memristors, pinched hysteresis loops and single line merging at high frequency, are systematically observed. A standard lock-in technique is used to probe the origin of this exotic behavior which cannot be explained here by a static resistance drop arising from joule heating. Rather the response appears to be associated with the formation of dynamic thermal impedance in the dissipative regime. Second, we observed a frequency dependent limit cycle and anomalous capacitance occurrence in SmB6 at low temperature where the insulating gap becomes fully opened. The limit cycle appears to be associated with autocatalytic temporal pattern formation as occurring in biological systems. And the measured anomalous capacitance indicates surface and bulk separation proposing surface conducting state formation. Both electrical properties may provide possible venues for parallel computation as artificial neuro-system and quantum computation. Possible follow-up experiments are discussed. And details on instrumentations used in this work are discussed with Scanning Probe Microscope software template which might be useful for the study of strongly correlated electron system.