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A family of models is proposed to describe the motion of holes in a fluctuating quantum dimer background on the square lattice. Following Castelnovo et al. [Ann. Phys. (N.Y.) 318, 316 (2005)], a generalized Rokhsar-Kivelson Hamiltonian at finite doping whi ...
The exponential localization of Wannier functions in two or three dimensions is proven for all insulators that display time-reversal symmetry, settling a long-standing conjecture. Our proof relies on the equivalence between the existence of analytic quasi- ...
We investigate the consequences of correlated hopping on the ground state properties of hard-core bosons on a square lattice as revealed by extensive exact diagonalizations and quantum Monte Carlo simulations. While for noninteracting hard-core bosons the ...
Using polarized neutron scattering we establish that the magnetic order in La1.48Nd0.4Sr0.12CuO4 is either (i) one dimensionally modulated and collinear, consistent with the stripe model or (ii) two dimensionally modulated with a novel noncollinear structu ...
This thesis reports on the design and construction of a novel experimental setup for the study of surface magnetic systems. This setup consists of a scanning tunneling microscope (STM) designed for ultra high vacuum (UHV) operating at T ≲ 1 K and str ...
We have extended the range of the high-pressure optical spectroscopy to the far-infrared region keeping the accuracy of ambient-pressure experiments. The developed method offers a powerful tool for the study of pressure-induced phase transitions and electr ...
Angle-resolved photoemission (ARPES) and optical measurements were performed on single crystal samples of LiCu2O2, an antiferromagnetic S=1/2 spin-chain compound. The ARPES spectra show several dispersive branches associated with hybrid copper-oxygen state ...
Starting from a single band Hubbard model in the Wannier function basis, we revisit the problem of the ligand contribution to exchange and derive explicit formulas for the exchange integrals in metal oxide compounds in terms of atomic parameters that can b ...
We investigate the properties of a two-dimensional frustrated quantum antiferromagnet on a square lattice, especially at infinitesimal doping. We find that next nearest neighbour (NN) J2 and next–next NN J3 interactions together destroy the antiferromagnet ...
Frustrated quantum magnets are a real challenge to theorists because standard analytical and numerical methods fail in most cases. Significant progress has been recently achieved however on the basis of what one may call minimal models, i.e. models which k ...
