Field-induced Criticality Research Articles

Electric field–induced criticality and frequency responsive dynamics of charged rods

We use the suspensions of charged fibrous virus (fd) as a model system for charged colloidal rods, where thick electric double layers are present. In particular, the system has shown the electric field–induced phase/state transitions under a low electric field strength. We briefly present the frequency responsive dynamics in the phase/state diagram and field-induced criticality in the dynamical states by approaching the field-induced critical point. In addition, the possible mechanism of low-frequency responsive dynamical states is briefly explained by the local charge redistribution of dissociation and association of condensed ions on the charged rods. The found phases/states are unique in the bulk phase diagram, away from the electrode polarization that is dominant near to the surface of the indium tin oxide glasses, in the sense that they are observed independent from the applied field amplitude and frequency.

Field-induced criticality in a gapped quantum magnet with bond disorder

Neutron diffraction and calorimetric measurements are used to study the field-induced quantum phase transition in piperazinium-Cu$_2$(Cl$_{1-x}$Br$_x$)$_6$ ($x=0$, x=3.5% and x=7.5%), a prototypical quantum antiferromagnet with random bonds. The critical indexes $\phi$ and $\beta$ are determined. The findings contradict some original predictions for Bose Glass based on the assumption $z=d$, but are consistent with recent theoretical results implying $z<d$. Inelastic neutron experiments reveal that disorder has a profound effect on the lowest-energy magnetic gap excitation in the system.