Abstract
We report the first example of tuning the large magneto-optic activity of a chiral polymer by addition of stable organic biradicals. The spectral dispersion of Verdet constant, which quantifies magneto-optic response, differs substantially between the base polymer and the nanocomposite. We employed a microscopic model, supported by atomistic calculations, to rationalize the behavior of this nanocomposite system. The suggested mechanism involves magnetic coupling between helical conjugated polymer fibrils, with spatially delocalized helical π-electron density, and the high density of spin states provided by the biradical dopants, which leads to synergistic enhancement of magneto-optic response. Our combined experimental and theoretical studies reveal that the manipulation of magnetic coupling in this new class of magneto-optic materials offers an opportunity to tailor the magnitude, sign, and spectral dispersion of the Verdet constant over a broad range of wavelengths, from the UV to the near-IR. This provides a new strategy for creating conformable materials with extraordinary magneto-optic activity, which can ultimately enable new applications requiring spatially and temporally resolved measurement of extremely weak magnetic fields. In particular, magneto-optic materials, presently employed in technologies like optical isolators and optical circulators, could be used in ultrasensitive optical magnetometers. This, in turn, could open a path toward mapping of brain activity via optical magnetoencephalography.
Original language | English |
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Pages (from-to) | 5451-5455 |
Number of pages | 5 |
Journal | Nano Letters |
Volume | 16 |
Issue number | 9 |
DOIs | |
Publication status | Published - Sep 14 2016 |
Externally published | Yes |
Keywords
- biradicals
- chirality
- Faraday rotation
- polymers
ASJC Scopus subject areas
- Bioengineering
- Chemistry(all)
- Materials Science(all)
- Condensed Matter Physics
- Mechanical Engineering