title: Critical Behavior of Alternately Pumped Nuclear Spins in Quantum Dots.
abstract: Nuclear spins in a spin-blocked quantum dot can be pumped and eventually polarized in either of two opposite directions that are selected by applying two different source-drain voltages. Applying a square pulse train as the source-drain voltage can continuously switch the pumping direction alternately. We propose and demonstrate a critical behavior in the polarization after alternate pumping, where the final polarization is sensitive to the initial polarization and pulse conditions. This sensitivity leads to stochastic behavior in the final polarization under nominally the same pumping conditions.
authors.affiliation: Center of Emergent Matter Science, RIKEN, 2-1 Hirosawa, Wako, Saitama 351-0198, Japan.|Department of Applied Physics, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan.
authors.forename: Y
authors.initials: Y
authors.lastname: Kondo
authors.affiliation: Center of Emergent Matter Science, RIKEN, 2-1 Hirosawa, Wako, Saitama 351-0198, Japan.
authors.forename: S
authors.initials: S
authors.lastname: Amaha
authors.affiliation: Center of Emergent Matter Science, RIKEN, 2-1 Hirosawa, Wako, Saitama 351-0198, Japan.|Low Temperature Physics Laboratory, RIKEN, 2-1 Hirosawa, Wako, Saitama 351-0198, Japan.
authors.forename: K
authors.initials: K
authors.lastname: Ono
authors.affiliation: Center of Emergent Matter Science, RIKEN, 2-1 Hirosawa, Wako, Saitama 351-0198, Japan.|Low Temperature Physics Laboratory, RIKEN, 2-1 Hirosawa, Wako, Saitama 351-0198, Japan.
authors.forename: K
authors.initials: K
authors.lastname: Kono
authors.affiliation: Center of Emergent Matter Science, RIKEN, 2-1 Hirosawa, Wako, Saitama 351-0198, Japan.|Department of Applied Physics, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan.
authors.forename: S
authors.initials: S
authors.lastname: Tarucha