Ordering Phenomena in Transition Metal Oxides

Field-induced quantum phase transitions in molecule-based materials   

Molecule-based quantum magnets offer exciting new possibilities for exploring quantum many-body effects under variable and well-controlled conditions. We focus here on a Cu^II-containing coordination polymer, which represents an excellent realization of an S = ½ Heisenberg chain with an intrachain exchange constant small enough for laboratory fields to tune the system across the saturation field. We will discuss results of the magnetocaloric effect on approaching the saturation field and compare the data with results of exact diagonalization and quantum Monte Carlo calculations on finite lattices.

Work done in collaboration with D. Jaiswal-Nagar, K. Removic-Langer, U. Tutsch, Y. Tsui, B. Wolf, A. Prokofiev, W. Assmus, G. Donath, and A. Honecker