  The resonant elements that grant metamaterials their unique properties have
the fundamental limitation of restricting their useable frequency bandwidth.
The development of frequency-agile metamaterials has helped to alleviate these
bandwidth restrictions by allowing real-time tuning of the metamaterial
frequency response. We demonstrate electrically-controlled persistent frequency
tuning of a metamaterial, allowing lasting modification of its response using a
transient stimulus. This work demonstrates a form of memory capacitance which
interfaces metamaterials with a class of devices known collectively as memory
devices.
