Reconfigurable Gradient Index using VO2 Memory Metamaterials
  We demonstrate tuning of a metamaterial device that incorporates a form of spatial gradient control. Electrical tuning of the metamaterial is achieved through a vanadium dioxide layer which interacts with an array of split ring resonators. We achieved a spatial gradient in the magnitude of permittivity, writeable using a single transient electrical pulse. This induced gradient in our device is observed on spatial sc ales on the order of one wavelength at 1 THz. Thus, we show the viability of elements for use in future devices with potential applications in beamforming and communications 
M. D. Goldflam, T. Driscoll, B. Chapler, O. Khatib, N. Marie Jokerst,   S. Palit, D. R. Smith, Bong-Jun Kim, Giwan Seo, Hyun...
cond-mat.mes-hall