Bulletin of the American Physical Society
APS March Meeting 2014
Volume 59, Number 1
Monday–Friday, March 3–7, 2014; Denver, Colorado
Session Z39: Invited Session: Strongly Correlated Electron Systems, Transition Metal Oxides, Vanadates |
Hide Abstracts |
Sponsoring Units: DCMP Chair: Dimitri Basov, University of California, San Diego Room: Mile High Ballroom 2A-3A |
Friday, March 7, 2014 11:15AM - 11:51AM |
Z39.00001: Giant reversible structural and electronic changes in liquid gated epitaxial films of VO2 Invited Speaker: Stuart S Parkin |
Friday, March 7, 2014 11:51AM - 12:27PM |
Z39.00002: Bad Metallic Behavior in Model Hamiltonian Studies and in Transition Metal Oxides Invited Speaker: Gabriel Kotliar We investigate the transport properties of a correlated metal within dynamical mean-field theory. Canonical Fermi liquid behavior emerges only below a very low temperature scale $T_{\mathrm{FL}}$. Surprisingly the quasiparticle scattering rate follows a quadratic temperature dependence up to much higher temperatures and crosses over to saturated behavior around a temperature scale $T_{\mathrm{sat}}$ indicating the existence of ``hidden'' Fermi liquid behavior. The non-Fermi-liquid transport above $T_{\mathrm{FL}}$, in particular the linear-in-$T$ resistivity, is shown to be a result of a strongly temperature dependent band dispersion. We derive simple expressions for the resistivity, Hall angle, thermoelectric power and Nernst coefficient in terms of a temperature dependent renormalized band structure and the quasiparticle scattering rate. We discuss the implications of the results for numerous transition metal oxides and other correlated materials connecting the non Fermi liquid transport with anomalous transfer of spectral weight. \\[4pt] References:\\[0pt] W Xu, K Haule, G Kotliar PRL 11 , 036401 (2013).\\[0pt] X Deng, J Mravlje, M Ferrero, G Kotliar, A Georges PRL 110, 086401 (2013).\\[0pt] B Lazarovits, K Kim, K Haule, G Kotliar, PRB 81, 115115(2010). [Preview Abstract] |
Friday, March 7, 2014 12:27PM - 1:03PM |
Z39.00003: Vanadium Dioxide: a reconfigurable disordered metamaterial Invited Speaker: Federico Capasso In VO$_{2}$ thin films, the Insulator-to-Metal transition occurs gradually with increasing temperature: Nanoscale inclusions of the metallic phase emerge in the surrounding insulating-phase VO$_{2}$, which grow and these metallic inclusions are much smaller than the scale of the wavelength at infrared frequencies, and thus VO$_{2}$ can be viewed as a natural, reconfigurable,disordered metamaterial with variable effective optical properties across the phase transition. connect in a percolation process, eventually leading to a fully metallic state at the end of the transition. In Ref. [1], this unique temperature-dependent dispersion of the effective medium was used to demonstrate that a film of VO$_{2}$, with thickness ( $\cong $ 150 nm) much smaller than the wavelength, deposited on sapphire can operate as a temperature tunable absorber; in particular, nearly perfect absorption was achieved at a particular temperature for a narrow range of infrared wavelengths. The reflectivity of such a device varies dramatically and non-monotonically across the phase transition, with the strong absorption feature appearing during an intermediate state of VO$_{2}$ as a result of coupling to an ``ultra-thin-film resonance'' [2]. Since the emissivity of an object is equal to its frequency-dependent absorptivity (Kirchoff's law) such a thin-film VO$_{2}$-sapphire structure is expected to have an emissivity that also depends strongly and non-monotonically on temperature. This structure displays ``perfect'' blackbody-like thermal emissivity over a narrow wavelength range (approximately 40 cm$^{-1})$, surpassing the emissivity of our black-soot reference [3]. We observed large broadband negative differential thermal emittance over a \textgreater 10 C range: Upon heating, the VO$_{\mathrm{2}}$-sapphire structure emits less thermal radiation and appears colder on an infrared camera [3]. Our experimental approach allows for a direct measurement and extraction of the wavelength- and temperature-dependent thermal emittance. Collaborations with M. A. Kats, S. Ramanathan, D. Sharma, R. Blanchard, P. Genevet, J. Lin, S. Zhang, C. Ko, Z. Yang, M. M. Qazilbash, D. N. Basov are gratefully acknowledged.\\[4pt] [1] M. A. Kats et al. Appl. Phys. Lett. 101,221101 (2012).\\[0pt] [2] M. A. Kats, R. Blanchard, P. Genevet, and F. Capasso, Nat. Mater. 12, 20 (2012).\\[0pt] [3] M. A. Kats et al. PRX 3, 041004 (2013). [Preview Abstract] |
Friday, March 7, 2014 1:03PM - 1:39PM |
Z39.00004: The metal-insulator triple point in vanadium dioxide Invited Speaker: David Cobden The metal-insulator transition (MIT) in vanadium dioxide is a candidate for optical and electrical switching applications. However, being a first-order solid-state phase transition makes it challenging to study reproducibly in any detail. The combination of the change in unit cell shape, symmetry reduction, long range of elastic distortion, and latent heat leads to domain structure, hysteresis, and cracking of even the highest quality samples. At the MIT two stable insulating phases (M1 and M2) occur in addition to the metallic phase (R), but their phase stability diagram was poorly known. To establish it precisely we studied single-crystal nanobeams of VO$_{\mathrm{2}}$ in a purpose-built nanomechanical strain apparatus. We were able to measure the transition temperature accurately to be 65.0 $+$- 0.1 $^{\mathrm{o}}$C, to determine the phase boundary slopes, and to detect the intermediate metastable triclinic (T) phase where it is metastable towards M2. We were surprised to find that the transition occurs precisely at the solid-state triple point of the metallic and two insulating phases, a fact that is not explained by existing theories. See J.H. Park et al, Nature 500, 431-4 (August 2013), doi:10.1038/nature12425. [Preview Abstract] |
Friday, March 7, 2014 1:39PM - 2:15PM |
Z39.00005: Ultrafast and Ultrasmall Spectroscopy of Phase Transition in VO$_{2}$ Invited Speaker: Mengkun Liu Recent advances in optical spectroscopy facilitate the probing of vibrational and electronic properties of materials with unprecedented spatial and time resolution (down to $\sim$ 10 nanometers and $\sim$ 10-s femtoseconds, respectively). In this talk, we report on ultrafast and ultrasmall aspects of the insulator-to-metal transition (IMT) in a canonical correlated electron material, vanadium dioxide (VO$_{2})$. Using scattering-type scanning near-field optical microscopy (s-SNOM) and spectroscopy (nano-FTIR), we revealed unidirectional conducting stripes in strained VO$_{2}$ films at sub-micrometer scale over a wide temperature range (320K-380K). Investigating the formation of this microscopic stripe state, we resolved the enigma of the macroscopic electronic anisotropy and disentangled three distinct stages of the VO$_{2}$ phase transition [Phys. Rev. Lett. 111 (9), 096602 (2013) and follow-up studies]. Furthermore, with newly developed terahertz (THz) pump THz probe spectroscopy, we demonstrated the first THz-field-induced insulator-to-metal switching experiments. We show that high-field THz pulses can effectively reduce the Coulomb-induced potential barrier for carrier transport and lead to subsequent rapid lattice heating. The fundamental electric-field-switching time of VO$_{2}$ can be in the order of a few picoseconds, with which the direct current measurements are incapable to measure due to instrumental limitations [Nature, 487, 345--348 (2012)]. With these comprehensive studies we offer unique insights into the electron and phonon evolution at fundamental time, energy and length scales. These novel spectroscopic techniques also provide universal methodologies for studying many other classes of transition metal oxides and phase transition materials. [Preview Abstract] |
Follow Us |
Engage
Become an APS Member |
My APS
Renew Membership |
Information for |
About APSThe American Physical Society (APS) is a non-profit membership organization working to advance the knowledge of physics. |
© 2024 American Physical Society
| All rights reserved | Terms of Use
| Contact Us
Headquarters
1 Physics Ellipse, College Park, MD 20740-3844
(301) 209-3200
Editorial Office
100 Motor Pkwy, Suite 110, Hauppauge, NY 11788
(631) 591-4000
Office of Public Affairs
529 14th St NW, Suite 1050, Washington, D.C. 20045-2001
(202) 662-8700