title: Large nuclear spin polarization in gate-defined quantum dots using a single-domain nanomagnet.
abstract: The electron-nuclei (hyperfine) interaction is central to spin qubits in solid state systems. It can be a severe decoherence source but also allows dynamic access to the nuclear spin states. We study a double quantum dot exposed to an on-chip single-domain nanomagnet and show that its inhomogeneous magnetic field crucially modifies the complex nuclear spin dynamics such that the Overhauser field tends to compensate external magnetic fields. This turns out to be beneficial for polarizing the nuclear spin ensemble. We reach a nuclear spin polarization of ≃50%, unrivaled in lateral dots, and explain our manipulation technique using a comprehensive rate equation model.
authors.affiliation: Center for Nanoscience and Fakultät für Physik, Ludwig-Maximilians-Universität München, Geschwister-Scholl-Platz 1, 80539 München, Germany.
authors.forename: Gunnar
authors.initials: G
authors.lastname: Petersen
authors.forename: Eric A
authors.initials: EA
authors.lastname: Hoffmann
authors.forename: Dieter
authors.initials: D
authors.lastname: Schuh
authors.forename: Werner
authors.initials: W
authors.lastname: Wegscheider
authors.forename: Geza
authors.initials: G
authors.lastname: Giedke
authors.forename: Stefan
authors.initials: S
authors.lastname: Ludwig