arXiv subjects

Zs. Gulacsi

Publications and source records attributed to Zs. Gulacsi.

3 recordsLinked to original sources

arXiv2001

New non-Fermi liquid type behavior given by a two-band system in normal phase

We are reporting a new non-Fermi liquid type normal phase that has a well defined Fermi energy, but without showing any non-regularity in the momentum distribution function in the whole momentum space, the sharp Fermi momentum concept being undefinable. The system contains a natural built in gap that is visible in the physical properties of the system at nonzero temperatures. The presence of a flat band in multiband interacting Fermi systems with more than half filling is the key feature leading to such a ground state, which is not restricted to one spatial dimension and emerges in the proximity of an insulating phase.

cond-mat.str-el↗

arXiv2001

Phase diagram regions deduced for strongly correlated systems via unitary transformation

From known phase diagram regions of different model Hamiltonians describing strongly correlated systems we deduced new domains of the ground state phase diagram of the same model by an unitary transformation. Different types of extended Hubbard Hamiltonians were used for the starting point and the existence of new stable spin-density wave, charge-density wave, ferromagnetic state and a paramagnetic insulator is demonstrated. The used procedure itself is dimension independent.

cond-mat.str-el↗

arXiv1998

Superconductivity in the Extended Hubbard Model with More Than Nearest-Neighbour Contributions

Superconducting phase diagram of the extended Hubbard model supplemented with interaction and hopping terms exceeding nearest neighbour distance in range is analysed systematically at different band-filling and temperature values in a mean-field approximation. The obtained results clearly underline the importance of next-nearest neighbour terms in developing the main superconducting properties of the model system. In particular, the emergence of superconducting phases of different symmetry at a given point of the phase diagram, critical temperatures $T_c$, zero temperature gap amplitude values $Δ_{0}$, $Δ_{0}/T_{c}$ ratios, doping and temperature dependences are all strongly influenced by next-nearest neighbour contributions.

cond-mat.str-el↗