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Title: Direct Measurements of Magnetic Polarons in Cd 1–xMn x Se Nanocrystals from Resonant Photoluminescence

In semiconductors, quantum confinement can greatly enhance the interaction between band carriers (electrons and holes) and dopant atoms. One manifestation of this enhancement is the increased stability of exciton magnetic polarons in magnetically doped nanostructures. In the limit of very strong 0D confinement that is realized in colloidal semiconductor nanocrystals, a single exciton can exert an effective exchange field B ex on the embedded magnetic dopants that exceeds several tesla. Here we use the very sensitive method of resonant photoluminescence (PL) to directly measure the presence and properties of exciton magnetic polarons in colloidal Cd 1–xMn xSe nanocrystals. Despite small Mn 2+ concentrations (x = 0.4–1.6%), large polaron binding energies up to ~26 meV are observed at low temperatures via the substantial Stokes shift between the pump laser and the resonant PL maximum, indicating nearly complete alignment of all Mn 2+ spins by B exex ≈ 10 T in these nanocrystals, in good agreement with theoretical estimates. Further, the emission line widths provide direct insight into the statistical fluctuations of the Mn 2+ spins. In conclusion, these resonant PL studies provide detailed insight into collective magnetic phenomena, especially in lightly doped nanocrystals where conventional techniques such as nonresonant PL ormore » time-resolved PL provide ambiguous results.« less
Authors:
 [1] ;  [2] ; ORCiD logo [3] ;  [4] ; ORCiD logo [2] ; ORCiD logo [2]
  1. Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Univ. of Wyoming, Laramie, WY (United States). Dept. of Physics and Astronomy
  2. Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
  3. Univ. degli Studi di Milano (Italy). Dipartimento di Scienza dei Materiali
  4. Technische Univ., Dortmund (Germany); Russian Academy of Sciences (RAS), St. Petersburg (Russian Federation). Ioffe Physical Technical Inst.
Publication Date:
Report Number(s):
LA-UR-17-20406
Journal ID: ISSN 1530-6984
Grant/Contract Number:
AC52-06NA25396
Type:
Accepted Manuscript
Journal Name:
Nano Letters
Additional Journal Information:
Journal Volume: 17; Journal Issue: 5; Journal ID: ISSN 1530-6984
Publisher:
American Chemical Society
Research Org:
Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
Sponsoring Org:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; 77 NANOSCIENCE AND NANOTECHNOLOGY; High Magnetic Field Science; nanocrystals, polaron
OSTI Identifier:
1364552

Rice, W. D., Liu, W., Pinchetti, V., Yakovlev, D. R., Klimov, V. I., and Crooker, S. A.. Direct Measurements of Magnetic Polarons in Cd1–xMnx Se Nanocrystals from Resonant Photoluminescence. United States: N. p., Web. doi:10.1021/acs.nanolett.7b00421.
Rice, W. D., Liu, W., Pinchetti, V., Yakovlev, D. R., Klimov, V. I., & Crooker, S. A.. Direct Measurements of Magnetic Polarons in Cd1–xMnx Se Nanocrystals from Resonant Photoluminescence. United States. doi:10.1021/acs.nanolett.7b00421.
Rice, W. D., Liu, W., Pinchetti, V., Yakovlev, D. R., Klimov, V. I., and Crooker, S. A.. 2017. "Direct Measurements of Magnetic Polarons in Cd1–xMnx Se Nanocrystals from Resonant Photoluminescence". United States. doi:10.1021/acs.nanolett.7b00421. https://www.osti.gov/servlets/purl/1364552.
@article{osti_1364552,
title = {Direct Measurements of Magnetic Polarons in Cd1–xMnx Se Nanocrystals from Resonant Photoluminescence},
author = {Rice, W. D. and Liu, W. and Pinchetti, V. and Yakovlev, D. R. and Klimov, V. I. and Crooker, S. A.},
abstractNote = {In semiconductors, quantum confinement can greatly enhance the interaction between band carriers (electrons and holes) and dopant atoms. One manifestation of this enhancement is the increased stability of exciton magnetic polarons in magnetically doped nanostructures. In the limit of very strong 0D confinement that is realized in colloidal semiconductor nanocrystals, a single exciton can exert an effective exchange field Bex on the embedded magnetic dopants that exceeds several tesla. Here we use the very sensitive method of resonant photoluminescence (PL) to directly measure the presence and properties of exciton magnetic polarons in colloidal Cd1–xMnxSe nanocrystals. Despite small Mn2+ concentrations (x = 0.4–1.6%), large polaron binding energies up to ~26 meV are observed at low temperatures via the substantial Stokes shift between the pump laser and the resonant PL maximum, indicating nearly complete alignment of all Mn2+ spins by Bexex ≈ 10 T in these nanocrystals, in good agreement with theoretical estimates. Further, the emission line widths provide direct insight into the statistical fluctuations of the Mn2+ spins. In conclusion, these resonant PL studies provide detailed insight into collective magnetic phenomena, especially in lightly doped nanocrystals where conventional techniques such as nonresonant PL or time-resolved PL provide ambiguous results.},
doi = {10.1021/acs.nanolett.7b00421},
journal = {Nano Letters},
number = 5,
volume = 17,
place = {United States},
year = {2017},
month = {4}
}