Graphene–ferroelectric metadevices for nonvolatile memory and reconfigurable logic-gate operations

• Published in: Nature communications 2016-01, Vol.7 (1), p.10429-10429, Article 10429
• Main Authors: Kim, Woo Young, Kim, Hyeon-Don, Kim, Teun-Teun, Park, Hyun-Sung, Lee, Kanghee, Choi, Hyun Joo, Lee, Seung Hoon, Son, Jaehyeon, Park, Namkyoo, Min, Bumki
• Format: Article
• Language: English
• Subjects: 142/126; 639/301/119/996; 639/301/357/1015; 639/766/400; 639/925/357/918; Ferroelectrics; Humanities and Social Sciences; multidisciplinary; Science; Science (multidisciplinary)
• ISSN: 2041-1723; 2041-1723
• DOI: 10.1038/ncomms10429

Memory metamaterials are artificial media that sustain transformed electromagnetic properties without persistent external stimuli. Previous memory metamaterials were realized with phase-change materials, such as vanadium dioxide or chalcogenide glasses, which exhibit memory behaviour with respect to electrically/optically induced thermal stimuli. However, they require a thermally isolated environment for longer retention or strong optical pump for phase-change. Here we demonstrate electrically programmable nonvolatile memory metadevices realised by the hybridization of graphene, a ferroelectric and meta-atoms/meta-molecules, and extend the concept further to establish reconfigurable logic-gate metadevices. For a memory metadevice having a single electrical input, amplitude, phase and even the polarization multi-states were clearly distinguishable with a retention time of over 10 years at room temperature. Furthermore, logic-gate functionalities were demonstrated with reconfigurable logic-gate metadevices having two electrical inputs, with each connected to separate ferroelectric layers that act as the multi-level controller for the doping level of the sandwiched graphene layer. Metamaterial memory devices often require a large stimulus to switch states or suffer from poor thermal stability. Here, the authors fabricate a terahertz metadevice driven by ferroelectric and graphene layers, and obtain multiple level memory devices stable at room temperature.