Andrzej M. Oles

Quantum melting of magnetic order due to orbital fluctuations

We have studied the phase diagram and excitations of the spin-orbital model derived for a three dimensional perovskite lattice, as in KCuF_3. The results demonstrate that the orbital degeneracy drastically increases quantum fluctuations and suppresses the classical long-range order near the multicritical point in the mean-field phase diagram. This generates a qualitatively new spin liquid, providing the first example of a valence bond ground state in three dimensions.

Electronic origin of magnetic and orbital ordering in in sulating LaMnO3

We derive a spin-orbital model for insulating

Fingerprints of spin-orbital physics in cubic Mott insulators: Magnetic exchange interactions and optical spectral weights

{\mathrm{LaMnO}}_{3}

One-dimensional metallic behavior of the stripe phase in La2-xSrxCuO4

which fulfills the SU(2) symmetry of

Unidirectional d -wave superconducting domains in the two-dimensional t − J model

S=2

Low-energy Mott-Hubbard excitations in LaMnO3 probed by optical ellipsometry

spins at

Quantum melting of magnetic long-range order near orbital degeneracy : Classical phases and Gaussian fluctuations

{\mathrm{Mn}}^{3+}

Quantum disorder versus order-out-of-disorder in the Kugel-Khomskii model

ions. It includes the complete

Orbital liquid in ferromagnetic manganites: The orbital Hubbard model for eg electrons

{e}_{g}

Microscopic origin of diagonal stripe phases in doped nickelates

and