Magnetic Domain Dependent Quantum Transport through a Ferromagnetic Dot Embedded in a Semiconductor Quantum Wire

Two unique quantum transport features, a clear appearance of Coulomb oscillations and a narrowing of Coulomb gap, are observed in an embedded ferromagnet (Ni) dot in a semiconductor wire after magnetic field application. Magnetic force microscopy analysis suggests the existence of a domain wall inside the dot before the field application, but it disappears after the field application forming a single domain in the dot. If we establish a transport model by assuming that the domain wall plays the role of a “resistive barrier,” we can explain those unique transport features in terms of “Coulomb blockade effects modified by domain dynamics.”