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Title: Enhanced Jahn-Teller response induced by low-dose 10 MeV I{sup +} irradiation of La{sub 0.7}Ca{sub 0.3}MnO{sub 3−δ} films

The structural response of pulsed laser deposited La{sub 0.7}Ca{sub 0.3}Mn0{sub 3−δ} films to low-level 10 MeV I{sup +} irradiation is correlated with magnetic and electronic properties. A series of annealed pulsed laser deposited films were subjected to ion irradiation at doses of 0.5–2.0 × 10{sup 13} 10 MeV iodine ions/cm{sup 2}. X-ray diffraction measurements show no measurable increase in the full width at half maximum values of major reflections before and after irradiation. Extended x-ray absorption fine structure analyses (EXAFS), employing both a model independent fitting using expanded cumulants as well as a nonlinear least squares multiple scattering model based on FEFF generated theoretical EXAFS data, were employed to measure local properties relative to the Mn ions. Increasing irradiation doses lead to an unambiguous evolution of MnO{sub 6} octahedra from highly symmetric (i.e., undistorted) to a clear bimodal structure in which the MnO{sub 6} octahedra are measured to undergo a c-axis stretching bearing resemblance to a Jahn-Teller distortion. Concomitantly, the metal to insulator transition temperature decreases more than 270 K and the magnetoresistance increases from 10{sup 2}% to 10{sup 6}%.
Authors:
;  [1] ; ; ; ; ;  [2] ; ;  [3] ;  [4]
  1. Department of Electrical and Computer Engineering, Northeastern University, Boston, Massachusetts 02115 (United States)
  2. U.S. Naval Research Laboratory, Code 6360, Washington, DC 20375 (United States)
  3. U.S. Naval Research Laboratory, Code 6340, Washington, DC 20375 (United States)
  4. Neocera, LLC, 10000 Virginia Manor Road, Beltsville, Maryland 20705 (United States)
Publication Date:
OSTI Identifier:
22300281
Resource Type:
Journal Article
Resource Relation:
Journal Name: Applied Physics Letters; Journal Volume: 104; Journal Issue: 21; Other Information: (c) 2014 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; ABSORPTION SPECTROSCOPY; ANNEALING; CALCIUM COMPOUNDS; FILMS; FINE STRUCTURE; IODINE IONS; ION BEAMS; JAHN-TELLER EFFECT; LANTHANUM COMPOUNDS; MAGNETORESISTANCE; MANGANATES; MANGANESE IONS; MANGANESE OXIDES; MEV RANGE 01-10; MULTIPLE SCATTERING; RADIATION DOSES; TRANSITION TEMPERATURE; X-RAY DIFFRACTION; X-RAY SPECTROSCOPY