Design of a semiconductor ferromagnet in a quantum-dot artificial crystal

We present the theoretical design of quantum-dot (QD) artificial ferromagnetic crystals. The electronic structure calculations based on local spin density approximation show that our designed QD artificial crystal from a structure comprising the crossing 0.104 mum wide InAs quantum wires (an effective Kagome lattice) has flat band characteristics. Our examined QD artificial crystal has the ferromagnetic ground state when the flat band is half filled, even though it contains no magnetic elements. The ferromagnetic and paramagnetic states can be freely switched by changing the electron filling via a gate voltage. (C) 2001 American Institute of Physics.