Reversible phototuning of the large anisotropic magnetization at the interface between a self-assembled photochromic monolayer and gold.

We have observed the emergence of a large anisotropic magnetization and significant photoinduced changes in the magentization that appear at the interface between a gold film and an azobenzene-containing self-assembled monolayer. The magnetization value was extremely high, up to 50 mu(B) per adsorbed molecule. These photomagnetic effects can be attributed to a photoinduced change in the loss of d charge due to photoisomerization of the azobenzene monolayer, which is accompanied by inversion of the surface dipoles. Furthermore, we have also observed reversible changes in the work function of the gold film by alternating UV and visible light, showing that the value of the surface dipole moment is changed as a result of photoisomerization. This allowed us to control the magnetization by alternating the photoillumination between UV and visible light, and we have clarified the mechanism for these photomagnetic effects. A novel strategy such as this, which enables significant reversible phototuning of the magnetic order, has great potential for applications in future magneto-optical devices.

[1]  Y. Einaga,et al.  Reversible Photoinduced Magnetization , 1997 .

[2]  Vladimiro Mujica,et al.  The injecting energy at molecule/metal interfaces: Implications for conductance of molecular junctions from an ab initio molecular description , 1999 .

[3]  Z. Vager,et al.  Magnetism induced by the organization of self-assembled monolayers , 2003 .

[4]  Paul Davids,et al.  Device model investigation of bilayer organic light emitting diodes , 2000 .

[5]  M. Rubner,et al.  Molecular heterostructure devices composed of langmuir-blodgett films of conducting polymers , 1992 .

[6]  W. Simpson,et al.  Assignment of Electronic Transitions in Azo Dye Prototypes , 1962 .

[7]  R Naaman,et al.  Direct detection of low-concentration NO in physiological solutions by a new GaAs-based sensor. , 2001, Chemistry.

[8]  Hiro Munekata,et al.  FERROMAGNETIC ORDER INDUCED BY PHOTOGENERATED CARRIERS IN MAGNETIC III-V SEMICONDUCTOR HETEROSTRUCTURES OF (IN,MN)AS/GASB , 1997 .

[9]  A. Shanzer,et al.  Molecular control over Au/GaAs diodes , 2000, Nature.

[10]  K. Tamada,et al.  Photoisomerization reaction of unsymmetrical azobenzene disulfide self-assembled monolayers: Modification of azobenzene dyes to improve thermal endurance for photoreaction , 2003 .

[11]  Ralph G. Nuzzo,et al.  Fundamental studies of microscopic wetting on organic surfaces. 1. Formation and structural characterization of a self-consistent series of polyfunctional organic monolayers , 1990 .

[12]  Y. Ozaki,et al.  Near-Infrared Surface-Enhanced Raman Scattering Study of Ultrathin Films of Azobenzene-Containing Long-Chain Fatty Acids on a Silver Surface Prepared by Silver Mirror and Nitric Acid Etched Silver Foil Methods , 1999 .

[13]  A. Ulman,et al.  Structure and binding of alkanethiolates on gold and silver surfaces: implications for self-assembled monolayers , 1993 .

[14]  A. Fujishima,et al.  Photoinduced magnetic pole inversion in a ferro-ferrimagnet: (Fe0.40IIMn0.60II) 1.5CrIII(CN)6 , 1997 .

[15]  Y. Einaga,et al.  Reversible photoswitching of ferromagnetic FePt nanoparticles at room temperature. , 2007, Journal of the American Chemical Society.

[16]  B. de Boer,et al.  Tuning of Metal Work Functions with Self‐Assembled Monolayers , 2005 .

[17]  Spiering,et al.  Strong Field Iron(II) Complex Converted by Light into a Long-Lived High-Spin State We are grateful for financial support from the TMR Research Network No. ERB-FMRX-CT98-0199, the Fonds der chemischen Industrie, and the University of Mainz (MWFZ). , 2000, Angewandte Chemie.

[18]  Y. Einaga,et al.  Photoswitchable magnetic nanoparticles of prussian blue with amphiphilic azobenzene , 2005 .

[19]  George M. Whitesides,et al.  Comparison of the Structures and Wetting Properties of Self-Assembled Monolayers of n- Alkanethiols on the Coinage Metal Surfaces, Cu, Ag, Au' , 1991 .

[20]  Kaoru Tamada,et al.  Photoreactivity in Self-Assembled Monolayers Formed from Asymmetric Disulfides Having para-Substituted Azobenzenes , 2003 .

[21]  Y. Einaga,et al.  Photocontrolled magnetization of CdS-modified Prussian blue nanoparticles. , 2006, Journal of the American Chemical Society.

[22]  C. B. Roberts,et al.  Magnetism in dodecanethiol-capped gold nanoparticles: Role of size and capping agent , 2007 .

[23]  Masahiro Irie,et al.  A Diarylethene with Two Nitronyl Nitroxides: Photoswitching of Intramolecular Magnetic Interaction , 2000 .

[24]  K. Tamada,et al.  Photoisomerization Reaction of Unsymmetrical Azobenzene Disulfide Self-Assembled Monolayers Studied by Surface Plasmon Spectroscopy: Influences of Side Chain Length and Contacting Medium , 2002 .

[25]  Y. Moritomo,et al.  Photoinduced demagnetization and its dynamical behavior in a (Nd 0.5 Sm 0.5 ) 0.6 Sr 0.4 MnO 3 thin film , 1998 .

[26]  R. Nuzzo,et al.  Temperature induced reconstruction of model organic surfaces , 1990 .

[27]  Y. Einaga,et al.  Photoswitchable magnetic layer-by-layer films consisting of azobenzene derivatives and iron oxide nanoparticles , 2005 .

[28]  S. Petralia,et al.  Monitoring photoswitching of azobenzene-based self-assembled monolayers on ultrathin platinum films by UV/Vis spectroscopy in the transmission modeElectronic supplementary information (ESI) available: synthesis and characterization of 1 and its photoisomerization in solution. See http://www.rsc.org/ , 2004 .

[29]  A. Ulman,et al.  Formation and Structure of Self-Assembled Monolayers. , 1996, Chemical reviews.

[30]  Richard L. Martin,et al.  CONTROLLING CHARGE INJECTION IN ORGANIC ELECTRONIC DEVICES USING SELF-ASSEMBLED MONOLAYERS , 1997 .

[31]  Y. Einaga,et al.  Observation of the anisotropic photoinduced magnetization effect in Co-Fe Prussian blue thin films fabricated by using clay Langmuir-Blodgett films as a template. , 2005, Journal of the American Chemical Society.

[32]  Dominique Vuillaume,et al.  Electron Transfer through a Monolayer of Hexadecylquinolinium Tricyanoquinodimethanide , 1999 .

[33]  Y. Einaga,et al.  Reversible photo-switching of the magnetization of iron oxide nanoparticles at room temperature. , 2004, Angewandte Chemie.

[34]  P. Gütlich,et al.  Photoswitchable coordination compounds , 2001 .

[35]  R. Naaman,et al.  Bosons as the origin for giant magnetic properties of organic monolayers. , 2004, Physical review letters.

[36]  A. Curioni,et al.  Density functional theory approach to thiols and disulfides on gold: Au(111) surface and clusters , 2000 .

[37]  Yoshio Taniguchi,et al.  Transparent organic light-emitting diodes using metal acethylacetonate complexes as an electron injective buffer layer , 2001 .

[38]  K. Seki,et al.  ENERGY LEVEL ALIGNMENT AND INTERFACIAL ELECTRONIC STRUCTURES AT ORGANIC/METAL AND ORGANIC/ORGANIC INTERFACES , 1999 .

[39]  P. Gütlich,et al.  Light-induced excited spin state trapping in a transition-metal complex: The hexa-1-propyltetrazole-iron (II) tetrafluoroborate spin-crossover system , 1984 .

[40]  Chen,et al.  Large On-Off Ratios and Negative Differential Resistance in a Molecular Electronic Device. , 1999, Science.

[41]  S. Koshihara,et al.  Fe-based magnetic-semiconductor hybrid structures for photocarrier-induced magnetism , 2000 .

[42]  R. Naaman,et al.  Organization-induced charge redistribution in self-assembled organic monolayers on gold. , 2005, The journal of physical chemistry. B.

[43]  D. Allara,et al.  Optical characterization of electronic transitions arising from the Au/S interface of self-assembled n-alkanethiolate monolayers , 1995 .

[44]  T. Yokoyama,et al.  X-ray magnetic circular dichroism of size-selected, thiolated gold clusters. , 2006, Journal of the American Chemical Society.

[45]  E. Tsymbal,et al.  The interface electronic structure of thiol terminated molecules on cobalt and gold surfaces , 2006 .

[46]  Y. Einaga,et al.  First observation of light-induced excited spin state trapping for an iron(III) complex [7] , 2000 .

[47]  H. Wolf,et al.  Photoswitching of Azobenzene Derivatives Formed on Planar and Colloidal Gold Surfaces , 1998 .

[48]  Amy L. Graham,et al.  Interface Dipoles Arising from Self-Assembled Monolayers on Gold: UV−Photoemission Studies of Alkanethiols and Partially Fluorinated Alkanethiols , 2003 .

[49]  A. Hernando,et al.  Permanent magnetism, magnetic anisotropy, and hysteresis of thiol-capped gold nanoparticles. , 2004, Physical review letters.

[50]  Y. Einaga,et al.  Photoswitchable Magnetic Films: Prussian Blue Intercalated in Langmuir−Blodgett Films Consisting of an Amphiphilic Azobenzene and a Clay Mineral , 2004 .

[51]  D. Milliron,et al.  Organic semiconductor interfaces: electronic structure and transport properties , 2000 .

[52]  M. Kryszewski,et al.  Polarized absorption spectroscopy of trans-azobenzene and trans-stilbene in stretched polyethylene films , 1990 .

[53]  Motohiro Suzuki,et al.  Reversible phototuning of ferromagnetism at Au-S interfaces at room temperature. , 2008, Angewandte Chemie.

[54]  T. Rojo,et al.  Chemically induced permanent magnetism in Au, Ag, and Cu nanoparticles: localization of the magnetism by element selective techniques. , 2008, Nano letters.

[55]  R. Naaman,et al.  New optical absorption band resulting from the organization of self-assembled monolayers of organic thiols on gold. , 2006, The journal of physical chemistry. B.

[56]  Stoddart,et al.  Electronically configurable molecular-based logic gates , 1999, Science.

[57]  Y. Einaga,et al.  Photofunctional Vesicles Containing Prussian Blue and Azobenzene , 1999 .

[58]  A. Fujishima,et al.  Photoinduced Magnetization of a Cobalt-Iron Cyanide , 1996, Science.