Tuning spin dynamics and localization near the metal-insulator transition in Fe/GaAs heterostructures
- The Ohio State Univ., Columbus, OH (United States)
- Univ. of Iowa, Iowa City, IA (United States)
- Univ. of California, Riverside, CA (United States)
- The Ohio State Univ., Columbus, OH (United States); Univ. of California, Riverside, CA (United States)
We present a simultaneous investigation of coherent spin dynamics in both localized and itinerant carriers in Fe/GaAs heterostructures using ultrafast and spin-resolved pump-probe spectroscopy. We find that for excitation densities that push the transient Fermi energy of photocarriers above the mobility edge there exist two distinct precession frequencies in the observed spin dynamics, allowing us to simultaneously monitor both localized and itinerant states. For low magnetic fields (below 3.00 T) the beat frequency between these two excitations evolves linearly, indicating that the nuclear polarization is saturated almost immediately and that the hyperfine coupling to these two states is comparable, despite the 20 times enhancement in nuclear polarization provided by the presence of the Fe layer. At higher magnetic fields (above 3.00 T) the Zeeman energy drives reentrant localization of the photocarriers. Subtracting the constant hyperfine contribution from both sets of data allows us to extract the Lande g factor for each state and estimate their energy relative to the bottom of the conduction band, yielding -2.16 and 17 meV for localized and itinerant states, respectively. This work advances our fundamental understanding of spin-spin interactions between electron and nuclear spin species, as well as between localized and itinerant electronic states, and therefore has implications for future work in both spintronics and quantum information/computation.
- Research Organization:
- The Ohio State Univ., Columbus, OH (United States)
- Sponsoring Organization:
- USDOE Office of Science (SC), Basic Energy Sciences (BES)
- Grant/Contract Number:
- FG02-03ER46054; SC0001304
- OSTI ID:
- 1480653
- Alternate ID(s):
- OSTI ID: 1478687
- Journal Information:
- Physical Review B, Vol. 98, Issue 13; ISSN 2469-9950
- Publisher:
- American Physical Society (APS)Copyright Statement
- Country of Publication:
- United States
- Language:
- English
Similar Records
Photon Echo from Localized Excitons in Semiconductor Nanostructures
TRANSIENT EXCITATION OF NUCLEI IN FERROMAGNETIC METALS