Transient Current in the Spin Blockade Region of a Double Quantum Dot

We investigate the slow transient buildup of leakage current influenced by dynamic spin polarization (DNP) in the spin blockade region of a double quantum dot (DQD). We focused on slightly off-resonant conditions, where the current is extremely small with nominally unpolarized nuclear spins. Leaving...

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Bibliographic Details
Published inJapanese Journal of Applied Physics Vol. 52; no. 11; pp. 110204 - 110204-2
Main Authors Sharmin, Sonia, Muraki, Koji, Fujisawa, Toshimasa
Format Journal Article
LanguageEnglish
Published The Japan Society of Applied Physics 01.11.2013
Subjects
Blocking
Construction
Dynamic tests
Dynamics
Leakage current
Nuclear spin
Polarization
Qunatum dots
Transient current
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Summary:We investigate the slow transient buildup of leakage current influenced by dynamic spin polarization (DNP) in the spin blockade region of a double quantum dot (DQD). We focused on slightly off-resonant conditions, where the current is extremely small with nominally unpolarized nuclear spins. Leaving the system in such a situation causes the current to increase stepwise twice . Such transient current steps can be understood by considering that at the first step inhomogeneous nuclear spin polarization significantly increases while at the second step stable polarization is attained. We believe that the DNP produces a feedback effect.
Bibliography:(Color online) (a) Schematic of the experimental device, which incorporates seven independently controlled gates. (b) and (c) Current $I$ as a function of $V_{\text{PL}}$ and $V_{\text{PR}}$ for $B = 0.1$ T. (Color online) (a) Schematic of electrochemical potentials in the spin blockade region. (b) Energy levels of the two-electron DQD system plotted as a function of the detuning $\varepsilon$. These energies are perturbed by $\Delta P$ (red dashed) and $\bar{P}$ (blue solid), respectively the difference and average of the nuclear spin polarizations in the left and right dots. (c) The leakage current as a function of detuning $\varepsilon$ and magnetic field $B$. (Color online) (a) Transient current $I(t)$ at different detunings. (b) Energy diagrams showing how the $(1,1)$ states gradually evolve with DNP. DNP is more efficient in the right dot for the example in (ii).
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ISSN:0021-4922
1347-4065
DOI:10.7567/JJAP.52.110204