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High Tc superconductivity in cuprates has engaged us for over 25 years. An apparent quantum complexityn arising from strong electron correlations and Mott physics, in the form of new experimental results, continues to challenge theorists. Intense efforts from theory has brought in a good and deep understanding of the optimal doped region of the phase diagram, particularly the superconducting phase. However, anomalous normal state in the optimal and under doped regime has defied simple theoretical understanding, partly because of nearly degenerate competing phases, differing structures and quantum chemistry among members of the cuprate family. But a standard model for the description of the winning superconducting phase is definitely there. There are also signals for some simplicity and new physic behind the complexity.
- G. Baskaran, The Institute of Mathematica Sciences Chennai
- Juan Carlos Campuzano, University of Illinois at Chicago
- Zheng-Cheng Gu, Perimeter Institute
- David Hawthorn, University of Waterloo
- Jiang-Ping Hu, Purdue University
- Sung-Sik Lee, Perimeter Institute & McMaster University
- Jia-Wei Mei, Perimeter Institute
- Yang Qi, Tsinghua University
- Subir Sachdev, Perimeter Institue & Harvard University
- Xiao-Gang Wen, Perimeter Institue and Massachusetts Institute of Technology
- Zheng-Yu Weng, Tsinghua University
Monday, July 6, 2015
Time |
Event |
Location |
10:00 – 11:00am |
G. Baskaran, The Institute of Mathematica Sciences Chennai |
Sky Room |
11:00 – 12:00pm |
Zheng-Yu Weng, Tsinghua University |
Sky Room |
Tuesday, July 7, 2015
Time |
Event |
Location |
10:00 – 11:00am |
Subir Sachdev, Perimeter Institute & Harvard University |
Sky Room |
11:00 – 12:00pm |
Zheng-Cheng Gu, Perimeter Institute |
Sky Room |
Wednesday, July 8, 2015
Time |
Event |
Location |
10:00 – 11:00am |
David Hawthorn, University of Waterloo |
Sky Room |
11:00 – 12:00pm |
Jiang-Ping Hu, Purdue University |
Sky Room |
2:00 – 3:30pm |
Colloquium: |
Theater |
Thursday, July 9, 2015
Time |
Event |
Location |
10:00 – 11:00am |
Xiao-Gang Wen, |
Sky Room |
11:00 – 12:00pm |
Yang Qi, Tsinghua University |
Sky Room |
Friday, July 10, 2015
Time |
Event |
Location |
10:00 – 11:00am |
Sung-Sik Lee, Perimeter Institute & McMaster University |
Sky Room |
11:00 – 12:00pm |
Jia-Wei Mei, Perimeter Institute |
Sky Room |
Ganapathy Baskaran, The Institute of Mathematical Sciences Chennai
Anderson-Haldane Liquid State in the Pseudogap Phase of Under Doped Cuprates and Two Leg t-J Ladder
Fractional spin-wave continuum in spin liquid states on the kagome lattice
Motivated by spin-wave continuum (SWC) observed in recent neutron scattering experiments in Herbertsmithite, we use Gutzwiller-projected wave functions to study dynamic spin structure factor of spin liquid states on the kagome lattice. As their ground state, spin-1 excited states for spin liquids are represented by Gutzwiller-projected two-spinon excited wave functions. We investigate three different spin liquid candidates, spinon Fermi-surface spin liquid (FSL), Dirac spin liquid (DSL) and random-flux spin liquid (RSL). We find that DSL has no explicit contradiction with experiments.
Anisotropic Non-Fermi Liquids
We study non-Fermi liquids that arise at the quantum critical points associated with the spin and charge density wave transitions in metals with the C2 symmetry. We use the dimensional regularization scheme, where a one-dimensional Fermi surface is embedded in 3 − epsilon dimensional momentum space. In three dimensions, marginal Fermi liquids arise at the spin and charge density wave critical points.
Coexistence of Antiferromagnetism and Superconductivity on Honeycomb Lattice
Motivated by results of DMRG and tensor network simulations on doped
$t$-$J$ model on honeycomb lattice, we study superconductivity of singlet and triplet pairing in this model. We show that a superconducting state with coexisting spin-singlet and spin-triplet pairings is induced by the antiferromagnetic order near half-filling. The superconducting state we obtain has a topological phase transition that separates a topologically trivial state and a non-trivial state with Chern number two.
Supperconductivity in t1-t2-J1-J2 model on Honeycomb lattice
We studied t1-t2-J1-J2 model on Honeycomb lattice at finite doping. We find that when t_1 is very small, the t1-t2-J1-J2 model on Honeycomb lattice may be in a supperconducting phase. Such a supperconducting phase is not driven by the pairing, but by entanglement.
Search the Genes of Unconventional High Temperature Superconductors
We discuss two basic principles to unify the understanding of both cuprates and iron-based superconductors: (1) the correspondence principle— the short range magnetic exchange interactions and the Fermi surfaces act collaboratively to achieve high Tc superconductivity and determine pairing symmetries; (2) the selective magnetic pairing rule: the superconductivity is only induced by the magnetic exchange couplings from the superexchange mechanism through cation-anion-cation chemical bondings but not those from direct exchange couplings resulted from the direct cation's d-d chemical bo
Nematicity and charge density wave order in stripe ordered cuprates probed via resonant x-ray scattering
In underdoped cuprate superconductors, a rich competition occurs between superconductivity and charge density wave order (CDW). Under debate, however, is whether rotational symmetry breaking (nematicity) also plays a central role -- whether it occurs intrinsically and generically or merely as a consequence of other orders. Here we employ resonant x-ray scattering in stripe-ordered (La,X)2CuO4 to probe the relationship between electronic nematicity of the Cu 3d orbitals, structural orthorhombicity of the (La,X)2O4 layers and CDW order.
A tensor product state approach to spin-1/2 square J1-J2 Heisenberg model: spin liquid vs. deconfined quantum criticality
The ground state phase diagram of spin-1/2 J1-J2 antiferromagnetic Heisenberg model on square lattice around the maximally frustrated regime (J2~0.5J1) has been debated for decades. I will discuss some progresses on this old problem based on recent numerical results from density matrix renormalization group(DMRG) and tensor product states algorithms.
The non-superconducting states of the cuprates
The most interesting states of the cuprate compounds are not the superconductors with high critical temperatures. Instead, the novelty lies primarily in the higher temperature metallic "normal" states from which the superconductors descend, and in competing low temperature states with density wave order. I will review recent experimental and theoretical progress in understanding these states. The experimental evidence is compatible with the presence of a metal with topological order in the 'pseudogap' regime of low carrier density.
Scientific Organizer:
Zheng-Cheng Gu, Perimeter Institute