ElusiveQuantum electronic materials: phases insights in correlated from near oxides field nano-optics and graphen insightD.N. Basov,from infraredColumbia nano-Universityscopy D.N. Basov Columbia University Support: Quantum materials: insights from near field nano-optics D.N. Basov, Columbia University Domain walls/ Weyl states CDW droplets / cuprates Phase separation / stripes Nd IrO HgBa CuO metal 2 7 2 4 V2O3 insulator 1 µm 2 µm 1 µm Ma et al. Campi et al. McLeod et al. Science 350, 538 (2015) Nature 525, 359 (2015) Nature Physics (2017) Edge currents & states 2DEG-QHE 1 µm Lai et al. PRL 107, 176809 (2011) λIR Quantum materials: insights from near field nano-optics D.N. Basov, Columbia University Outline: Why nano-light? “Complete” response function Phase transitions at the nanoscale σ(ω,t,x,q ) McLeod et al. Nature Physics (2017) Jang et al. Nature Materials (2016) delay Light-matter polaritons & search for Berry plasmons Ni et al. Nature Phot 10 244 (16) Basov et al. Science (2016) probe Guangxin Ni et al. Nature Photonics 10, 244 (2016) Quantum materials: insights from near field nano-optics D.N. Basov, Columbia University Outline: Why nano-light? K K’ t=0 Phase transitions at the nanoscale McLeod et al. Nature Physics (2017) Jang et al. Nature Materials (2016) Light-matter polaritons & search for Berry plasmons nm Ni et al. Nature Phot 10 244 (16) delay Basov et al. Science (2016) probe with C. Dean, J. Hone, M. Fogler & T. Low Quantum materials: insights from near field nano-optics D.N. Basov, Columbia University Outline: Why nano-light? Phase transitions at the nanoscale McLeod et al. Nature Physics (2017) Jang et al. Nature Materials (2016) Light-matter polaritons & search for Berry plasmons Ni et al. Nature Phot 10 244 (16) Basov et al. Science (2016) Quantum materials and infrared nano-optics V2O3 100 GHz 1000 100 meV 1000 Density Phonons Plasmons m Spins Superfluids Excitons µ waves – + – – + – – – – – – – – – 10 – + – Cyclotron modes and Landau Level transions Correlated Drude response metal Metals insulator Magne8c resonances phonons Inter-band transions Superconduc8ng gap polarons McLeod et al Nature Physics (2016) Fe- & Cu-based superconductors (pseudo)gap in cuprates Charge transfer gap Magne8c resonances Hund’s coupling Van der Waals Josephson plasmons (anisotropic) plasmons Excitons & gap: MX ……. semiconductors Hyperbolic phonon polaritons 2 cyclotron resonance & LLs Excitons & gap: bP Topological insulators Surface & bulk plasmons & Weyl metals bulk 1ML helicons phonons Inter-band transions Tunable Fermi Energy EF Graphene Tunable band gap in bilayer & band parameters Dirac plasmons 1 10 100 1000 10000 cm-1 -1 IR wavelength: Wavenumbers, cm 1000 µm 100 µm 10 µm D.N. Basov, M.Fogler, A.Lanzara, F. Wang and Y. Zhang, RMP 86, 959 (2014) D.N. Basov, R.A. Averitt, D. van der Marel, M. Dressel, K. Haule RMP 83, 471 (2011) D.N. Basov and A,V. Chubukov Nature-Physics 7, 272 (2011) Quantum materials and infrared nano-optics V2O3 100 GHz 1000 100 meV 1000 Density Phonons Plasmons m Spins Superfluids Excitons µ waves – + – – + – – – – – – – – – 10 – + – Cyclotron modes and Landau Level transions Correlated Drude response metal Metals insulator Magne8c resonances phonons Inter-band transions Superconduc8ng gap polarons McLeod et al Nature Physics (2016) Fe- & Cu-based superconductors (pseudo)gap in cuprates Charge transfer gap Magne8c resonances Hund’s coupling Van der Waals Josephson plasmons (anisotropic) plasmons Excitons & gap: MX ……. semiconductors Hyperbolic phonon polaritons 2 cyclotron resonance & LLs Excitons & gap: bP Topological insulators Surface & bulk plasmons & Weyl metals bulk 1ML helicons phonons Inter-band transions Tunable Fermi Energy EF Graphene IR Tunable band gap in bilayer & band parameters Dirac plasmons 1 10 100 1000 10000 cm-1 -1 IR wavelength: Wavenumbers, cm Δx 1000 µm 100 µm 10 µm x < 8-10 nm << D.N. Basov, M.Fogler, A.Lanzara, F. Wang and Y. Zhang, RMP 86, 959 (2014) Δ λ D.N. Basov, R.A. Averitt, D. van der Marel, M. Dressel, K. Haule RMP 83, 471 (2011) D.N. Basov and A,V. Chubukov Nature-Physics 7, 272 (2011) σ(ω,t,x,q) Quantum materials: insights from infrared nano-optics D.N. Basov, Columbia University Outline: Why nano-light? Phase transitions at the nanoscale McLeod et al. Nature Physics (2017) Jang et al. Nature Materials (2016) Light-matter polaritons & search for Berry plasmons V2O3 Ni et al. Nature Phot 10 244 (16) Basov et al. Science (2016) 10 µm metal insulator McLeod et al Nature Physics (2016) V2O3: a prototypical Mott insulator Low-T High-T J. Phys.: Condens. Matter 21 (2009) 355401 CMeneghiniet al J. Phys.: Condens. Matter 21 (2009) 355401Monoclinic CMeneghiniet al Corundum AFI ordering Figure 2. Schematic view of the experimental set-up. Data were Figure 2. Schematic view of the experimental set-up. Data were collected with x-ray polarization (ϵ)inthehexagonalplane(ϵ c ), ⊥ H collected with x-ray polarization (ϵ)inthehexagonalplane(ϵ cH), i.e. along x and y (top) and parallel to the hexagonal C axis cH ⊥ Figure 1. Schematic view of V2O3 structures: only V ions are shown i.e. along x and y (top) and parallel to the hexagonal C axis cH (bottom). The fluorescence emission was collected using two Figure 1. Schematic view of V2O3 structures: only V ions are shown for the sake of clarity. Left: the hexagonal cell with the trigonal for the sake of clarity. Left: the hexagonal cell with the trigonal (bottom). The fluorescence emission was collected using two photodiodes (P). photodiodes (P). (primitive) cell inside; right: relationship between corundum (room (primitive) cell inside; right: relationship between corundum (room temperature PM phase) and monoclinic (low temperature AFI phase) temperature PM phase) and monoclinic (low temperature AFI phase) unit cells. X-ray absorption measurements were performed aligning collected at the ID26 beamline of the European Synchrotron unit cells. X-ray absorption measurements were performed aligning collected at the ID26 beamline of the European Synchrotron the x-ray beam polarization along the three orthogonal directions of Radiation Facility (ESRF) in the fluorescence mode. The x-ray the x-ray beam polarization along the three orthogonal directions of Radiation Facility (ESRF) in the fluorescence mode. The x-ray the hexagonal lattice: the c axis and, perpendicular to it, the x and y the hexagonal lattice: the c axis and, perpendicular to it, the x and y beam energies were selected using a double-crystal Si(220), beam energies were selected using a double-crystal Si(220), (corresponding to the monoclinic bm axis, see the text) directions (corresponding to the monoclinic bm axis, see the text) directions highlighted on the left. fixed-exit monochromator, providing an energy resolution of highlighted on the left. fixed-exit monochromator, providing an energy resolution of 0.3eVattheVK-edge. Energyscansweredonein 0.3eVattheVK-edge. Energyscansweredonein ∼ ∼ the so-called gap-scan mode, that is, tuning the maximum the so-called gap-scan mode, that is, tuning the maximum though the AFI and PI phases were reported, respectively, as of the undulator emission to the actual monochromator though the AFI and PI phases were reported, respectively, as of the undulator emission to the actual monochromator monoclinic and trigonal by x-ray diffraction studies [7], in [23] rocking curve. Two mirrors provided an harmonic-free, monoclinic and trigonal by x-ray diffraction studies [7], in [23] rocking curve. Two mirrors provided an harmonic-free, no evident differences were found for the local structure in small (diameter 300 µm), intense x-ray spot size on the no evident differences were found for the local structure in small (diameter 300 µm), intense x-ray spot size on the ∼ ∼ the two phases and both were fitted better by the monoclinic sample, linearly polarized in the horizontal plane. The the two phases and both were fitted better by the monoclinic sample, linearly polarized in the horizontal plane. The structure than by the trigonal one. Even though we basically fluorescence intensity emitted from the sample was collected in structure than by the trigonal one. Even though we basically fluorescence intensity emitted from the sample was collected in agree with the analysis of [23], two key ingredients were still the total-fluorescence mode by measuring the current from two agree with the analysis of [23], two key ingredients were still the total-fluorescence mode by measuring the current from two missing in their treatment for a full characterization of the PI photodiodes (figure 2), mounted parallel to the polarization of missing in their treatment for a full characterization of the PI photodiodes (figure 2), mounted parallel to the polarization of phase, i.e. a full temperature dependence study of the signal, the incoming beam in order to minimize the elastic contribution phase, i.e. a full temperature dependence study of the signal, the incoming beam in order to minimize the elastic contribution and a comparative study of the behavior of first-and further- to the spectrum and the self-absorption effect [28]. and a comparative study of the behavior of first-and further- to the spectrum and the self-absorption effect [28]. nearest neighbors. In particular, since the measurements The 2.8% chromium-doped V2O3 single crystal was nearest neighbors. In particular, since the measurements The 2.8% chromium-doped V2O3 single crystal was of [23]inthePIphasewerecollectedatatemperature mounted in a closed-cycle He refrigerator for temperature of [23]inthePIphasewerecollectedatatemperature