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Current-controlled instantaneous molecular switching Sasha Alexandrov

Current-controlled instantaneous molecular switching Sasha Alexandrov Loughborough University, UK Molecular switching Lattice polaron and bipolaron, and multi-polaron problem MQD with electron-vibron and Coulomb interactions

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Current-controlled instantaneous molecular switching Sasha Alexandrov

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  1. Current-controlled instantaneous molecular switching • Sasha Alexandrov • Loughborough University, UK • Molecular switching • Lattice polaron and bipolaron, and multi-polaron problem • MQD with electron-vibron and Coulomb interactions • MQD density of states: correlation and vibron side-bands • Non-linear rate equation • Current switching of a degenerate MQD: molecular memory effect • Alexandrov, A.S., Bratkovsky, A.M. and Stanley Williams, R., ''Bistable Tunneling Current Through a Molecular • Quantum Dot'' , Physical Review B , 67 , 2003, 075301. • Alexandrov, A.S. and Bratkovsky, A. M., ''Memory Effect in a Molecular Quantum Dot with Strong Electron-Vibron • Interaction'' , Physical Review B , 67 , 2003, 235312. • Alexandrov, A.S., '‘Polarons in Complex Oxides and Molecular Nanowires'' , in Molecular Nanowires and Other • Quantum Objects (Kluwer Academic Pub. ), 151 (2004).

  2. Molecular Electronic Devices A.Aviram and M.A. Ratner, Chem. Phys. Lett.29 (1974) 277; R.M. Metzger, Acc. Chem. Res. 32 (1999) 950; C.P. Collier et al. Science 285 (1999) 391… There are broad categories of molecular switching behavior: • Electric-field control molecular switching • Electromechanical molecular switching • Photoactive molecular switching   • Electrochemical molecular switching Strong attractive electron correlations in molecules may result in a novel current-control instantaneous molecular switching

  3. + + N N M e O O O S M e S S O N O O M e O O O S S O S O O S O O O N N + + — M e O O O 4 P F 6 M e O O O S M e S S O N O O M e O O O S S O S O O S O O O M e O O O + + N N M e O O O O S M e S S O O O M e O O O N O S S S O O O – 4 P F 6 M e O O O N N + + Universal molecular switch behaviour rotaxane corresponding dumbbell rotaxane (reversed) Adapted from D. Stewart et al., submitted to APL (2002). Pt-Ti leads

  4. HP researchers have created a 64-bit laboratory prototype memory in a space one micron square - an area so tiny that more than 1,000 could fit across the end of a single strand of human hair The wafer on which 625 memories and their test structures were simultaneously imprinted. A single test structure with the memory An array of memories with their test connections Nanowires leading from the test pins to the memory at the intersection of the lines. A close-up of a single 64-bit memory. A bit can be stored at each of the intersections of the eight vertical and eight horizontal wires. The crossed-wire structure of the memory.

  5. Motivation Strong electron-phonon (vibron) interaction in molecules results in effective attraction of two electrons Adapted from A.S. Alexandrov and P.E. Kornilovitch, J.Phys.:Condens. Matter 14 (2002) 5337.

  6. Some literature: Large (continues) polaron: Landau L D 1933 J. Phys.} (USSR)} 3 664; Pekar S I 1946 Zh. Eksp. Teor. Fiz. 16 335; Froehlich H 1954 Adv. Phys. 3 325; Feynman R P 1955 Phys. Rev. 97 660; Rashba E I 1957 Opt. Spectr. 2 75; 1985 Excitons (eds. Rashba E I and Struge D M, Moscow: Nauka); Devreese J T 1996 in Encyclopedia of Applied Physics, vol. 14 p. 383 (VCH Publishers). Small (lattice) polaron: Tjablikov S V 1952 Zh.Eksp.Teor.Fiz 23 381; Yamashita J and T. Kurosawa 1958 J. Phys.Chem. Solids 5 34; Sewell G L 1958 Phil. Mag. 3 1361; Holstein T 1959 Ann. Phys. 8 325; 343; Friedman L and Holstein T 1963 Ann. Phys. 21 494; Emin D and Holstein T 1969 Ann. Phys. 53 439; Lang I G and Firsov Yu A 1962 Sov. Phys. JETP 16 1301; Eagles D M 1963 Phys. Rev. 130 1381; Appel J 1968 in Solid State Physics 21 (eds. Seitz F, Turnbull D and Ehrenreich H, Academic Press); Firsov Yu A (ed) 1975 Polarons, (Moscow: Nauka); Boettger H and Bryksin V V 1985 Hopping Conduction in Solids (Berlin: Academie-Verlag); Mahan G D 1990 Many Particle Physics (New York: Plenum Press); Alexandrov A S and Mott N F 1995 Polarons and Bipolarons, World Scientific. Large bipolaron: Vinetskii V L and Gitterman M Sh 1961 Sov. Phys. JETP 13 1023; Suprun S G and Moizhes B Ya 1982 Sov. Phys. Solid State 24 903; Adamowskii J 1989 Phys. Rev. B39 3649; Bassani F et al. 1991 Phys. Rev. B43 5296; Verbist G, Peters F M and Devreese J T 1991 Phys. Rev. B43 2712 … Small bipolaron: Anderson P W 1975 Phys. Rev. Lett. 34 953 ; Street R A and Mott N F 1975 Phys. Rev. Lett. 35 1293; Chakraverty B K 1979 J. Phys. Lett. (Paris)40 L-99 Multi-polaron problem: Alexandrov A S and Ranninger J 1981 Phys. Rev. B23 1796; Alexandrov A S 1983 Russ. J. Phys. Chem. 57 167; Bednorz J G and Mueller K A 1988 Angew. Chem. Int. Ed. Engl. 27 735; Alexandrov A S 1992 Phys. Rev. B 46 14932; Aubry S 1995 in Polarons and Bipolarons in High-Tc Superconductors and Related Materials (eds. Salje E K H, Alexandrov A S and Liang W Y, Cambridge: Cambridge University Press) p. 271; Bishop A R and Salkola M 1995 ibid, p. 353; Marsiglio F 1995 Physica C 244 21; Takada Y and Higuchi T 1995 Phys. Rev. B52 12720; Millis A J, Littlewood P B and Shraiman B I, Phys. Rev. Lett. 74 5144; Baesens C and MacKay RS 1997 J MATH PHYS 38 2104; Fehske H, Loos J, and Wellein G 1997 Z. Phys. B104 619; Benedetti P and Zeyher R 1998 Phys. Rev. B58 14320 ; Bonca J, Trugman S A, and Batistic I 1999 Phys. Rev. B60, 1633; Alexandrov A S and Bratkovsky 1999 Phys. Rev. Lett. 82 141; Proville L and Aubry S 1999 Eur. Phys. J. B 11 41; Alexandrov A S 2000 Phys. Rev. B61 12315; Alexandrov A S 2003 Theory of superconductivity: from weak to strong coupling, IoP Publishing.

  7. Mobile bipolarons can be the current carriers Adapted from A.S. Alexandrov and P.E. Kornilovitch, J.Phys.:Condens. Matter 14 (2002) 5337.

  8. MQD with electron-vibron and Coulomb interactions D eV< 2D Landauer-type expression for steady current through MQD:

  9. MQD weakly coupled with leads, exact solution H=Smem nm +1/2 Sm,n Vc nm nn+gw0 Smnm (d+d+)+ w0 (d+d+1/2)

  10. Exact solution continues

  11. Green’s function of d-fold degenerate MQD

  12. DOS: correlation and vibron side-bands

  13. Non-linear rate equation Fermi-Dirac Golden rule:

  14. 4-fold degenerate MQD compared with d>>1 -fold degenerate dot: negative Hubbard U model

  15. Switching with electron-vibron coupling

  16. Current-control instantaneous switching D eV< 2D J=0 Switching occurs in the voltage range 2(D-|U|) < eV < 2D J=2n D-|U| eV> 2D no correlations with the attractive correlations

  17. Conclusions: • Transport in molecular nanowires could be strongly affected by the interaction with ion vibrations • There are phonon-side bands and attractive electron-electron correlations due to the strong electron-phonon (vibron) interaction in MQD • There is a current-controlled instantaneous molecular switching due to attractive electron correlations in the degenerate (d>2) MQD

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