Abdollah Langari – Physics Department – Sharif University of Technology

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Contact

Room 233

P.O.Box: 11155-9161

Phone: +98 21 6616 4572

Fax: +98 21 6602 2711

E-Mail: langari@sharif.edu

Personal Page

Group Page

Research Interests

Strongly Correlated Electron Systems, Quantum Magnetism

Research Plan

Strongly correlated electron systems cover a wide class of materials and models that show unusual electronic and magnetic properties such as metal-insulator and high-Tc superconductivity. The common feature of this systems is the existence of strong correlations between the electrons which can not be explained effectively in terms of single particle picture. The ground state is the most important state which is responsible for the exotic behavior in strongly correlated electron systems.
Our main research interest is the investigation of ground state phase diagram of such models specially for magnetic materials. The classification of different phases and quantum phase transition between them are part of our investigations. Quantum phase transitions are induced by the change of an external parameter or coupling constant, and are driven by quantum fluctuations. The role of quantum correlations can be understood in terms of quantum information properties of the model. This motivate us to look for the quantum information aspects of a quantum phase transition. We also investigate the exact ground state of some spin models.
We implement both numerical (exact diagonalization Lanczos, density matrix renormalization group) and analytical methods (quantum renormalization group, spin wave theory) in our study.

Selected Publications

Factorized ground state for a general class of ferrimagnets
Phys. Rev. B. 81, 060401 (R) (2010)
M. Rezai, A. Langari and J. Abouie

Dzyaloshinskii-Moriya Interaction and Anisotropy effects on the Entanglement of Heisenberg Model
Phys. Rev. A 79, 042319 (2009)
M. Kargarian, R. Jafari, A. Langari

Renormalization of concurrence: The application of the quantum renormalization group to quantum-information systems
Phys. Rev. A. 76, 90304 (R) (2007)
M. Kargarian ,R. Jafari and A. Langari

Anti-ferromagnetic and spin-gap phases of the anisotropic Kondo necklace model
Phys. Rev. B.74, 24431 (2006)
A. Langari and P. Thalmeier

Quantum renormalization group of XYZ model in a transverse magnetic field
Phys. Rev. B69, 100402(R) (2004)
A. Langari