Tuning spin dynamics and localization near the metal-insulator transition in Fe/GaAs heterostructures

Yu-Sheng Ou; N. J. Harmon; Patrick Odenthal; R. K. Kawakami; M. E. Flatte; E. Johnston-Halperin

doi:10.1103/PhysRevB.98.134444

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Tuning spin dynamics and localization near the metal-insulator transition in Fe/GaAs heterostructures

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Tuning spin dynamics and localization near the metal-insulator transition in Fe/GaAs heterostructures

Yu-Sheng Ou, N. J. Harmon, Patrick Odenthal, R. K. Kawakami, M. E. Flatte and E. Johnston-Halperin

Physical review. B, Vol.98(13), p.134444

10/24/2018

DOI: 10.1103/PhysRevB.98.134444

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Abstract

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.

Materials Science

Physical Sciences

Physics

Technology

Materials Science, Multidisciplinary

Physics, Applied

Physics, Condensed Matter

Science & Technology

Details

Title: Subtitle: Tuning spin dynamics and localization near the metal-insulator transition in Fe/GaAs heterostructures
Creators: Yu-Sheng Ou - The Ohio State University
N. J. Harmon - University of Iowa
Patrick Odenthal - University of California, Riverside
R. K. Kawakami - University of California, Riverside
M. E. Flatte - University of Iowa
E. Johnston-Halperin - The Ohio State University
Resource Type: Journal article
Publication Details: Physical review. B, Vol.98(13), p.134444
DOI: 10.1103/PhysRevB.98.134444
ISSN: 2469-9950
eISSN: 2469-9969
Publisher: Amer Physical Soc
Number of pages: 6
Grant note: DE-SC0001304 / U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences; United States Department of Energy (DOE) DMR-1420451 / Center for Emergent Materials: an NSF MRSEC; National Science Foundation (NSF)
Language: English
Date published: 10/24/2018
Academic Unit: Electrical and Computer Engineering; Physics and Astronomy
Record Identifier: 9984428766202771

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