We predict that a quantum-dot lattice is formed in a quantum wire network and exhibits ferromagnetism. A theoretical calculation based on a local spin density approximation shows that quantum dots can be formed on the crossings of 0.104 micrometer-wide InAs quantum wires, which form a Kagome lattice having a flat band. This dot lattice has the ferromagnetic ground state when the flat band is half-filled, even though it contains no magnetic elements. We also demonstrate that the ferromagnetism can be turned on and off in a controllable manner by changing the electron filling.
[Reference: Applied Physics Letters 78, 3702 (2001).]

=> Spintronics Research Group