Electron number dependence of spin triplet–singlet relaxation time

• The relaxation time of spin singlet–triplet states for the last few even electron numbers has been studied.
• The singlet–triplet energy separation EST is tuned for the comparison of T1 between different electron numbers.
• T1 steadily decreases with increasing electron numbers from 2-electrons to 6-electrons.
• T1 was found to substantially decrease due to the enhanced spin–orbit coupling strength.

In a GaAs single quantum dot, the relaxation time T1 between spin triplet and singlet states has been measured for the last few even electron numbers. The singlet–triplet energy separation EST is tuned as a control parameter for the comparison of T1 between different electron numbers. T1 steadily decreases with increasing electron numbers from 2-electrons to 6-electrons. This implies an enhancement of the spin–orbit coupling strength due to multi-electron interaction in a quantum dot.