This page includes selected results from our research. You can navigate between different subjects listed below. For a complete list of publications go to the publications page.
Spin-glass
The Blume-Emery-Griffiths spin glass is studied by renormalization-group theory in d=3. The boundary between the ferromagnetic and paramagnetic phases has first-order and two types of second-order segments. This topology includes an inverted tricritical point, first-order transitions replacing second-order transitions as temperature is lowered. The phase diagrams show disconnected spin-glass regions, spin-glass and paramagnetic reentrances, and complete reentrance, where the spin-glass phase replaces the ferromagnet as temperature is lowered for all chemical potentials.
Quantum Phase Transitions from RG theory: Hubbard Model
The Hubbard Model with hard-core bosons and fermions is studied on a 3-dimensional lattice using a position-space renormalization-group (RG) procedure. For both cases the global phase diagrams in the interaction space and the expectation values are calculated. In the system with fermions, totally symmetric phase diagrams are found consisting of four phases two of which disappear as the attraction between sites increases. In the system with bosons, seven phases are present five of which exist only at low temperatures and disappear as the attraction between sites increases. All phase transitions are second order and disconnected phases are present at low temperature values.
