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

We present the theoretical design of quantum-dot (QD) artificial ferromagne tic crystals. The electronic structure calculations based on local spin den sity approximation show that our designed QD artificial crystal from a stru cture comprising the crossing 0.104 mum wide InAs quantum wires (an effecti ve Kagome lattice) has flat band characteristics. Our examined QD artificia l crystal has the ferromagnetic ground state when the flat band is half fil led, even though it contains no magnetic elements. The ferromagnetic and pa ramagnetic states can be freely switched by changing the electron filling v ia a gate voltage. (C) 2001 American Institute of Physics.