Magnetoelectrically Controlled Valley Filter and Valley Valve in Bilayer Graphene

In the quest for what might replace conventional electronics, the emerging field of $v{{0}{0ex}}a{{0}{0ex}}l{{0}{0ex}}l{{0}{0ex}}e{{0}{0ex}}y{{0}{0ex}}t{{0}{0ex}}r{{0}{0ex}}o{{0}{0ex}}n{{0}{0ex}}i{{0}{0ex}}c{{0}{0ex}}s$ (capitalizing on local extrema in a semiconductor's band structure for information processing) is a contender. Here the valley filter and valley valve are two key elements, and it is important to combine them in a unit. The authors present a simple, viable model for such a unit, based on bilayer graphene. Device operation is based on valley-contrasting transmission, due to the valley Zeeman effect and a band gap tunable by gate voltage, by which nearly perfect filtering and very high valve efficiency are achieved. This system could yield a reversible NAND gate, for example.