Regensburg 2010 – wissenschaftliches Programm
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TT: Fachverband Tiefe Temperaturen
TT 33: TR: Nanoelectronics I: Quantum Dots, Wires, Point Contacts 2
TT 33.14: Vortrag
Donnerstag, 25. März 2010, 17:30–17:45, H19
Control of Spin Blockade by AC Magnetic Fields in Triple Quantum Dots — •Maria Busl1, Rafael Sánchez2, and Gloria Platero1 — 1Instituto de Ciencia de Materiales Madrid, CSIC, 28049 Cantoblanco Madrid, Spain — 2Département de Physique Théorique, Université de Genève, CH-1211 Genève 4, Switzerland
We analyze theoretically transport through a triangular triple quantum dot (TQD) determined by the interplay of coherent phenomena coming from dc and ac magnetic fields. A dc magnetic field applied perpendicularly to the dot area induces a flux Φ. In triangular TQDs with one extra electron, it was shown [1, 2] that current can be blocked when the electron drops into an eigenstate that is decoupled from transport, a so-called dark state. This blocking in turn can be destroyed by the flux piercing the TQD. We show that in a triangular TQD with two extra electrons, current will be blocked either by the formation of a two-electron dark state or by Pauli spin blockade, depending on the flux Φ. Spin blockade can be broken by ac magnetic fields, and a finite current can be generated [3]. Unexpectedly however, we demonstrate that an ac magnetic field is not only able to break spin blockade but also to induce it again, at a particular field frequency ω. Hence applying an ac magnetic field is a way of controlling spin blockade in a TQD [4].
[1] C. Emary, Phys. Rev. B 76, 245319 (2007).
[2] M. Busl et al., Physica E (in press).
[3] F.H.L. Koppens et al., Nature 442, 766 (2006).
[4] M. Busl et al., arXiv:0907.0182.