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

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, andmore » therefore has implications for future work in both spintronics and quantum information/computation.« less

Authors:
 [1];  [2];  [3];  [4];  [2];  [1]
  1. The Ohio State Univ., Columbus, OH (United States)
  2. Univ. of Iowa, Iowa City, IA (United States)
  3. Univ. of California, Riverside, CA (United States)
  4. The Ohio State Univ., Columbus, OH (United States); Univ. of California, Riverside, CA (United States)
Publication Date:
Research Org.:
The Ohio State Univ., Columbus, OH (United States)
Sponsoring Org.:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
OSTI Identifier:
1480653
Alternate Identifier(s):
OSTI ID: 1478687
Grant/Contract Number:  
FG02-03ER46054; SC0001304
Resource Type:
Journal Article: Accepted Manuscript
Journal Name:
Physical Review B
Additional Journal Information:
Journal Volume: 98; Journal Issue: 13; Journal ID: ISSN 2469-9950
Publisher:
American Physical Society (APS)
Country of Publication:
United States
Language:
English
Subject:
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; Spin; spintronics; magnetism; semiconductor; hyperfine; coherent; ultrafast

Citation Formats

Ou, Yu-Sheng, Harmon, N. J., Odenthal, Patrick, Kawakami, R. K., Flatté, M. E., and Johnston-Halperin, E. Tuning spin dynamics and localization near the metal-insulator transition in Fe/GaAs heterostructures. United States: N. p., 2018. Web. doi:10.1103/PhysRevB.98.134444.
Ou, Yu-Sheng, Harmon, N. J., Odenthal, Patrick, Kawakami, R. K., Flatté, M. E., & Johnston-Halperin, E. Tuning spin dynamics and localization near the metal-insulator transition in Fe/GaAs heterostructures. United States. doi:10.1103/PhysRevB.98.134444.
Ou, Yu-Sheng, Harmon, N. J., Odenthal, Patrick, Kawakami, R. K., Flatté, M. E., and Johnston-Halperin, E. Wed . "Tuning spin dynamics and localization near the metal-insulator transition in Fe/GaAs heterostructures". United States. doi:10.1103/PhysRevB.98.134444.
@article{osti_1480653,
title = {Tuning spin dynamics and localization near the metal-insulator transition in Fe/GaAs heterostructures},
author = {Ou, Yu-Sheng and Harmon, N. J. and Odenthal, Patrick and Kawakami, R. K. and Flatté, M. E. and Johnston-Halperin, E.},
abstractNote = {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.},
doi = {10.1103/PhysRevB.98.134444},
journal = {Physical Review B},
issn = {2469-9950},
number = 13,
volume = 98,
place = {United States},
year = {2018},
month = {10}
}

Journal Article:
Free Publicly Available Full Text
This content will become publicly available on October 24, 2019
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