Inflection point as a manifestation of tricritical point on the dynamic phase boundary in Ising meanfield dynamics

TL;DR

This paper investigates the dynamic phase transition in a mean-field Ising model under oscillating magnetic fields, identifying an inflection point as a tricritical point that marks the change in transition nature.

Contribution

The study reveals that the inflection point on the phase boundary corresponds to the tricritical point, providing a simpler method to locate it in mean-field dynamics.

Findings

Phase boundary inflates with increasing frequency.

Inflection point acts as a tricritical point separating transition types.

Tricritical point shifts to higher fields at higher frequencies.

Abstract

We studied the dynamical phase transition in kinetic Ising ferromagnet driven by oscillating magnetic field in meanfield approximation. The meanfield differential equation was solved by sixth order Runge-Kutta-Felberg method. We calculated the transition temperature as a function of amplitude and frequency of the oscillating field. This was plotted against field amplitude taking frequency as a parameter. As frequency increases the phase boundary is observed to become inflated. The phase boundary shows an inflection point which separates the nature of the transition. On the dynamic phase boundary a tricritical point (TCP) was found, which separates the nature (continuous/discontinuous) of the dynamic transition across the phase boundary. The inflection point is identified as the TCP and hence a simpler method of determining the position of TCP was found. TCP was observed to shift towards high field for higher frequency. As frequency decreases the dynamic phase boundary is observe to shrink. In the zero frequency limit this boundary shows a tendency to merge to the temperature variation of the coercive field.