Seminarium Fizyki Materii Skondensowanej

The Majumdar-Ghosh model is a spin-1/2 chain and one of the few frustrated magnetic models with an exactly solvable ground state. In our study, we look at its q-deformation, a deformation respecting the U_q(su(2)) symmetry of the model. The q-deformation allows us to explore an unusual system offering a bridge between (q=0) transverse field Ising (integrable model) and (q=1) Majumdar- Ghosh model. We derive exact formulas for the dimer order parameter in finite size and in the thermodynamic limit and compare them to numerical results from ED and DMRG. Moreover, we compute numerically several expectation values including magnetisation, ground state energy, and von Neumann entropy in transversal and longitudinal magnetic fields. These measurements give different perspectives on looking at this model and may offer a way to confirm a possible experimental realization in the material Szenicsite.