Quantum critical dynamics in the presence of disorder

Quantum phase transitions are abrupt qualitative changes of a system's groundstate occurring only at exactly zero temperature. Such critical points - although never reachable – in their vicinity strongly impact many physical properties, even at comparably high temperatures. In fact, properties of many exotic materials are now linked to quantum phase transitions and these are studied intensely. Magnetic insulators make excellent model systems for such studies, as it is often possible to induce quantum phase transitions by applying a strong magnetic field or hydrostatic pressure. In the proposed experiment we study a compound that is quantum critical even at ambient fields and pressure as the quantum phase transition occurs as a function of chemical composition.