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Title: Colossal terahertz magnetoresistance at room temperature in epitaxial La 0.7Sr 0.3MnO 3 nanocomposites and single-phase thin films

Colossal magnetoresistance (CMR) is demonstrated at terahertz (THz) frequencies by using terahertz time-domain magnetospectroscopy to examine vertically aligned nanocomposites (VANs) and planar thin films of La 0.7Sr 0.3MnO 3. At the Curie temperature (room temperature), the THz conductivity of the VAN was dramatically enhanced by over 2 orders of magnitude under the application of a magnetic field with a non-Drude THz conductivity that increased with frequency. The direct current (dc) CMR of the VAN is controlled by extrinsic magnetotransport mechanisms such as spin-polarized tunneling between nanograins. In contrast, we find that THz CMR is dominated by intrinsic, intragrain transport: the mean free path was smaller than the nanocolumn size, and the planar thin-film exhibited similar THz CMR to the VAN. Surprisingly, the observed colossal THz magnetoresistance suggests that the magnetoresistance can be large for alternating current motion on nanometer length scales, even when the magnetoresistance is negligible on the macroscopic length scales probed by dc transport. This suggests that colossal magnetoresistance at THz frequencies may find use in nanoelectronics and in THz optical components controlled by magnetic fields. As a result, the VAN can be scaled in thickness while retaining a high structural quality and offers a larger THz CMRmore » at room temperature than the planar film.« less
Authors:
ORCiD logo [1] ;  [1] ;  [2] ;  [1] ; ORCiD logo [3] ;  [4] ;  [5] ;  [5]
  1. Univ. of Warwick, Coventry (United Kingdom)
  2. Univ. of Oxford, Oxford (United Kingdom)
  3. Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
  4. Univ. at Buffalo, Buffalo, NY (United States)
  5. Univ. of Cambridge, Cambridge (United Kingdom)
Publication Date:
Report Number(s):
LA-UR-17-22535
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: 4; Journal ID: ISSN 1530-6984
Publisher:
American Chemical Society
Research Org:
Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
Sponsoring Org:
USDOE Laboratory Directed Research and Development (LDRD) Program
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; 77 NANOSCIENCE AND NANOTECHNOLOGY; Material Science
OSTI Identifier:
1364556