Energy transfer and electronic transport in zigzag graphene nanoribbons exhibit spin-polarized effects upon application of an electric field across the nanoribbon width. However, the electric fields required to experimentally induce this  magnetic state are typically large and difficult to apply in practice. Using both experimental characterization1 and first-principles DFT methods,2 we show that a new spiropyran-based, mechanochromic polymer noncovalently deposited on a nanoribbon  can collectively function as a dual opto-mechanical switch for  modulating its own spin-polarization. Our findings demonstrate  that upon mechanical stress or photoabsorption, the spiropyran chromophore  isomerizes from a closed-configuration ground-state to a zwitterionic  excited-state, resulting in a large change in dipole moment that alters  the electrostatic environment of the nanoribbon. We show that the electronic spin-distribution in the nanoribbon-spiropyran hybrid material can be reversibly modulated via noninvasive optical and mechanical stimuli without the need for large  external electric fields. Our results show that the reversible  spintronic properties inherent to the nanoribbon-spiropyran  material allow the possibility of using this hybrid structure as a  resettable, molecular-logic quantum sensor where opto-mechanical stimuli  are used as inputs and the spin-polarized current induced in the nanoribbon substrate is the measured output.1. G. O'Bryan, B. M. Wong, and J. R. McElhanon, ACS Appl. Mater. Interfaces 2  , 1594 (2010).2. B. M. Wong, S. H. Ye, and G. O'Bryan, Nanoscale 4  , 1321 (2012). 

Energy transfer and opto-mechanically induced spin-switching in nanoribbon-spiropyran hybrid materials

244th National Meeting (2012)

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