We use reflective probing of transient linear birefringence to study coherent exciton dynamics in GaAs quantum wells as a function of applied magnetic field at low temperatures. The results show the significance of exchange-enhanced exciton spin relaxation for dephasing at zero field. In applied field the signals show background-free quantum beating which gives the exciton g factor and field-dependent dephasing time. The latter is dominated by spin relaxation which shows for the first time the dramatic slowdown predicted in earlier work.We use reflective probing of transient linear birefringence to study coherent exciton dynamics in GaAs quantum wells as a function of applied magnetic field at low temperatures. The results show the significance of exchange-enhanced exciton spin relaxation for dephasing at zero field. In applied field the signals show background-free quantum beating which gives the exciton g factor and field-dependent dephasing time. The latter is dominated by spin relaxation which shows for the first time the dramatic slowdown predicted in earlier work.

Physical Review LettersApr 22, 199655 citations

Spin relaxation in GaAs multiple quantum wells: well-width dependence

Peggy Perozzo, Alan Miller

Time-resolved excite-probe measurements were performed on GaAs multiple quantum wells to determine the spin relaxation time as a function of well width (L) at room temperature, and as a function of temperature in the range of 10 to 150 K. These studies suggest that the room temperature spin relaxation time follows an exponential well width dependence, indicating that at room temperature spin flip is dominated by a combination of the D'Yakonov-Perel and the Bir-Aronov-Pikus mechanisms. The low temperature results suggest that a different mechanism, the exchange interaction, is dominant at low temperatures.Time-resolved excite-probe measurements were performed on GaAs multiple quantum wells to determine the spin relaxation time as a function of well width (L) at room temperature, and as a function of temperature in the range of 10 to 150 K. These studies suggest that the room temperature spin relaxation time follows an exponential well width dependence, indicating that at room temperature spin flip is dominated by a combination of the D'Yakonov-Perel and the Bir-Aronov-Pikus mechanisms. The low temperature results suggest that a different mechanism, the exchange interaction, is dominant at low temperatures.

Proceedings of SPIE, the International Society for Optical Engineering/Proceedings of SPIEApr 19, 19963 citations

Probing and controlling spin-relaxation in GaAs quantum wells

Y. Ohno, R. Terauchi, T Adachi +2 more

Springer proceedings in physicsJan 1, 20010 citations

Zeeman relaxation of magnetically trapped Eu atoms

Yury V. Suleimanov

We perform rigorous quantum mechanical calculations for collisions between magnetically trapped Eu atoms to elucidate the results of recent experimental studies. We show that the relaxation from the maximally stretched ${m}_{s}=7/2$ level is entirely determined by the magnetic dipole-dipole interaction and analyze the role of the electronic spin-exchange interaction in transitions from the lower-energy Zeeman levels. The relaxation of the ${m}_{s}=5/2$ state is shown to be very sensitive to the spin-exchange parameter that determines the splitting between the lowest electronic states of the Eu dimer. We suggest that cold collision experiments with trapped atoms can be used as a tool for obtaining accurate information on the electronic spin anisotropy in complex molecules such as Eu ${}_{2}$ .We perform rigorous quantum mechanical calculations for collisions between magnetically trapped Eu atoms to elucidate the results of recent experimental studies. We show that the relaxation from the maximally stretched ${m}_{s}=7/2$ level is entirely determined by the magnetic dipole-dipole interaction and analyze the role of the electronic spin-exchange interaction in transitions from the lower-energy Zeeman levels. The relaxation of the ${m}_{s}=5/2$ state is shown to be very sensitive to the spin-exchange parameter that determines the splitting between the lowest electronic states of the Eu dimer. We suggest that cold collision experiments with trapped atoms can be used as a tool for obtaining accurate information on the electronic spin anisotropy in complex molecules such as Eu${}_{2}$.

Physical Review AFeb 3, 201010 citations

{m}_{s}=7/2

level is entirely determined by the magnetic dipole-dipole interaction and analyze the role of the electronic spin-exchange interaction in transitions from the lower-energy Zeeman levels. The relaxation of the

{m}_{s}=5/2

state is shown to be very sensitive to the spin-exchange parameter that determines the splitting between the lowest electronic states of the Eu dimer. We suggest that cold collision experiments with trapped atoms can be used as a tool for obtaining accurate information on the electronic spin anisotropy in complex molecules such as Eu

{}_{2}