From the Hubbard model to high temperature superconductivity HARVARD S. Sachdev Talk online: sachdev.physics.harvard.edu
Max Metlitski: Entanglement near strongly interacting quantum critical points in two and higher dimensions Yang Qi: Frustrated antiferromagnetism and spin liquids in organic insulators Posters HARVARD
The cuprate superconductors
Central ingredients in cuprate phase diagram: antiferromagnetism, superconductivity, and change in Fermi surface
Antiferro- magnetism Fermi surface d-wave supercon- ductivity
Central ingredients in cuprate phase diagram: antiferromagnetism, superconductivity, and change in Fermi surface
N. E. Hussey, J. Phys: Condens. Matter 20, (2008) Crossovers in transport properties of hole-doped cuprates
Strange metal Crossovers in transport properties of hole-doped cuprates Pseudo- gap
Strange metal Crossovers in transport properties of hole-doped cuprates Pseudo- gap
How is antiferromagnetism lost with increasing doping ? How does the Fermi surface evolve with loss of antiferromagnetism ? Do antiferromagnetic fluctuations induce d-wave superconductivity ? How does attraction between antiferromagnetism and superconductivity turn into competition ? Is there a broken symmetry in the pseudo-gap regime ? What is the role of nematic/valence-bond-solid/stripe order ? What is the physics of the strange metal ? Questions
Antiferro- magnetism Fermi surface d-wave supercon- ductivity
Antiferro- magnetism Fermi surface d-wave supercon- ductivity
Ground state has long-range Néel order Square lattice antiferromagnet
J J/ Weaken some bonds to induce spin entanglement in a new quantum phase
Square lattice antiferromagnet J J/ Ground state is a “quantum paramagnet” with spins locked in valence bond singlets
Pressure in TlCuCl 3
Quantum critical point with non-local entanglement in spin wavefunction
Spin waves
Christian Ruegg, Bruce Normand, Masashige Matsumoto, Albert Furrer, Desmond McMorrow, Karl Kramer, Hans–Ulrich Gudel, Severian Gvasaliya, Hannu Mutka, and Martin Boehm, Phys. Rev. Lett. 100, (2008) TlCuCl 3 with varying pressure
Christian Ruegg, Bruce Normand, Masashige Matsumoto, Albert Furrer, Desmond McMorrow, Karl Kramer, Hans–Ulrich Gudel, Severian Gvasaliya, Hannu Mutka, and Martin Boehm, Phys. Rev. Lett. 100, (2008) TlCuCl 3 with varying pressure
Christian Ruegg, Bruce Normand, Masashige Matsumoto, Albert Furrer, Desmond McMorrow, Karl Kramer, Hans–Ulrich Gudel, Severian Gvasaliya, Hannu Mutka, and Martin Boehm, Phys. Rev. Lett. 100, (2008) TlCuCl 3 with varying pressure
Prediction of quantum field theory
Christian Ruegg, Bruce Normand, Masashige Matsumoto, Albert Furrer, Desmond McMorrow, Karl Kramer, Hans–Ulrich Gudel, Severian Gvasaliya, Hannu Mutka, and Martin Boehm, Phys. Rev. Lett. 100, (2008)
Antiferro- magnetism Fermi surface d-wave supercon- ductivity
Antiferro- magnetism Fermi surface d-wave supercon- ductivity
“Large” Fermi surfaces in cuprates Hole states occupied Electron states occupied
Spin density wave theory
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Electron pockets Hole pockets Electron-doped cuprates S. Sachdev, A. V. Chubukov, and A. Sokol, Phys. Rev. B 51, (1995). A. V. Chubukov and D. K. Morr, Physics Reports 288, 355 (1997). D. Senechal and A.-M. S. Tremblay, Phys. Rev. Lett. 92, (2004)
N. P. Armitage et al., Phys. Rev. Lett. 88, (2002). Photoemission in NCCO
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Nature 450, 533 (2007) Quantum oscillations
Theory of quantum criticality in the cuprates
Antiferro- magnetism Fermi surface d-wave supercon- ductivity
Antiferro- magnetism Fermi surface d-wave supercon- ductivity
Theory of quantum criticality in the cuprates
Criticality of the coupled dimer antiferromagnet at x=x s
Theory of quantum criticality in the cuprates Criticality of the topological change in Fermi surface at x=x m
Theory of quantum criticality in the cuprates
++ _ _ D. J. Scalapino, E. Loh, and J. E. Hirsch, Phys. Rev. B 34, 8190 (1986) K. Miyake, S. Schmitt-Rink, and C. M. Varma, Phys. Rev. B 34, 6554 (1986)
Theory of quantum criticality in the cuprates
How is antiferromagnetism lost with increasing doping ? How does the Fermi surface evolve with loss of antiferromagnetism ? Do antiferromagnetic fluctuations induce d-wave superconductivity ? How does attraction between antiferromagnetism and superconductivity turn into competition ? Is there a broken symmetry in the pseudo-gap regime ? What is the role of nematic/valence-bond-solid/stripe order ? What is the physics of the strange metal ? Questions
Max Metlitski: Entanglement near strongly interacting quantum critical points in two and higher dimensions Yang Qi: Frustrated antiferromagnetism and spin liquids in organic insulators Posters HARVARD