Spectral and transport properties of ballistic quantum wire exposed to two magnetic spikes

Quantum Dots (QD) in two-dimensional electron gases are typically defined by nanopatterned gate electrodes.\footnote{see, e.g., L. P. Kouwenhoven et al., in Mesoscopic Electron Transport, Series E: Applied Sciences (Eds. L. L. Sohn, L. P. Kouwenhoven and G. Schon (Kluwer, 1997).} While magnetically confined QDs have been proposed theoretically to show some specific phenomena,\footnote{S.J. Lee et al., Phys. Rep. \textbf{394}, 1 (2004)} their experimental implementation is still at an early stage.\footnote{A. Tarasov et al., Phys. Rev. Lett. \textbf{104}, 186801 (2010)} We have designed a ferromagnet/semiconductor hybrid structure device which allows us to form a QD by combining electrostatic potentials with localized magnetic fields in the form of two magnetic spikes at sub-micron distances. While numerical simulations of this system predict Coulomb blockade in the closed regime and Fano type resonances in the open system,\footnote{H. Xu et al. Phys. Rev. B \textbf{84}, 035319 (2011)} we observe experimentally transmission resonances in the open system which can be interpreted as signatures of zero-dimensional states weakly bound by the magnetic field profile.