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Lifting of spin blockade by hyperfine interaction in vertically coupled double quantum dots
Author(s) -
Tarucha S.,
Kitamura Yosuke,
Kodera Tetsuo,
Ono Keiji
Publication year - 2006
Publication title -
physica status solidi (b)
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.51
H-Index - 109
eISSN - 1521-3951
pISSN - 0370-1972
DOI - 10.1002/pssb.200642290
Subject(s) - hyperfine structure , zeeman effect , quantum dot , singlet state , zeeman energy , excited state , atomic physics , triplet state , condensed matter physics , pauli exclusion principle , spin flip , spin (aerodynamics) , chemistry , energy level splitting , exchange interaction , magnetic field , physics , quantum mechanics , ferromagnetism , scattering , thermodynamics
The ability of the hyperfine interaction to lift spin blockade was studied for vertically coupled double quantum dots in two different regimes of potential detuning between the two dots. The double dot has a triplet state, which is a sufficiently long‐lived excited state to block current flow by the Pauli effect. This blockade is lifted by a spin flip transition to the singlet state, generating a leakage current. The singlet‐triplet separation or exchange energy decreases with increasing detuning. For small detuning, the leakage current shows a step when the Zeeman energy equals the exchange energy thus turning on the flip‐flop interaction. The threshold magnetic field gradually increases with decreasing detuning. It increases more abruptly near the resonance of two singlet states reflecting the increased exchange energy. For large detuning, the leakage current is caused by singlet‐triplet mixing due to the fluctuating nuclear field, and it decreases when the Zeeman energy exceeds the fluctuating nuclear field energy. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)