nanoGUNE Colloquium: Probing correlated electron matter by infrared nano-spectroscopy and nano-imaging

CIC nanoGUNE Seminars

Prof. D.N. Basov, University of California San Diego
nanoGUNE seminar room, Tolosa Hiribidea 76, Donostia - San Sebastian
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nanoGUNE Colloquium: Probing correlated electron matter by infrared nano-spectroscopy and nano-imaging **Host** : Txema Pitarke One common attribute of several classes of correlated electron systems is that the insulator-to-metal transition in these systems typically occurs in the regime of nano-scale phase separation of chemical, and/or electronic/magnetic origin [1]. These intrinsic non-uniformities complicate the inquiry into the roles of lattice/structural transformations and many body physics in the emergence of metallicity. Despite rapid progress with the development of scanning probe techniques, it remains a challenging task to _simultaneously_ probe nano-scale variations of electronic and structural properties over macroscopic regions [2]. We have accomplished this task using advanced nano- infrared methods that we have applied to investigate crystalline films of a prototypical correlated oxide VO2. Recent experiments [3] have allowed us to visualize the route cause of the electronic anisotropy and memory effects [4] in this material. Through nano-spectroscopic monitoring of the lattice and free carrier dynamics in VO2 we uncovered three different stages of the insulator-to-metal transition characterized by distinct electron-lattice effects. [1] D. N. Basov, Richard D. Averitt, Dirk van der Marel, Martin Dressel, and Kristjan Haule “[ _Electrodynamics of correlated electron materials_]( ” Reviews of Modern Physics 83, 471 (2011) [2] Dawn A. Bonnell, D. N. Basov, Matthias Bode, Ulrike Diebold, Sergei V. Kalinin, Vidya Madhavan, Lukas Novotny, Miquel Salmeron, Udo D. Schwarz, and Paul S. Weiss “[ _Imaging physical phenomena with local probes: From electrons to photons_](” Reviews of Modern Physics 84, 1343 (2012). [3] Mengkun Liu, Martin Wagner, Elsa Abreu, Salinporn Kittiwatanakul, Alexander McLeod, Zhe Fei, Michael Goldflam, Siyuan Dai, Michael Fogler, Jiwei Lu, Stuart A. Wolf, Richard D. Averitt, D. N. Basov, “Anisotropic electronic state via spontaneous phase separation in strained Vanadium Dioxide films” (under review). [4] T.Driscoll, H.T. Kim, B.G. Chae, B.J. Kim, N. Marie Jokerst, S. Palit, D.R. Smith, M. Di Ventra, D.N. Basov “ _Memory Metamaterials_ ” Science 325, 1518 (2009). D.N. Basov, University of California San Diego