Dynamic transitions and hysteresis

TL;DR

This paper reviews the phenomena of dynamic hysteresis and phase transitions in many-body systems driven by time-dependent external fields, highlighting the conditions under which symmetry breaking and non-zero averages occur.

Contribution

It provides an overview of recent research on dynamic hysteresis and phase transitions, emphasizing the mechanisms of symmetry breaking in driven many-body systems.

Findings

Dynamic hysteresis depends on driving frequency, amplitude, and temperature.

Transitions to symmetry-broken phases occur beyond certain threshold frequencies.

Various types of external fields can induce similar dynamic transitions.

Abstract

When an interacting many-body system, such as a magnet, is driven in time by an external perturbation, such as a magnetic field,the system cannot respond instantaneously due to relaxational delay. The response of such a system under a time-dependent field leads to many novel physical phenomena with intriguing physics and important technological applications. For oscillating fields, one obtains hysteresis that would not occur under quasistatic conditions in the presence of thermal fluctuations. Under some extreme conditions of the driving field, one can also obtain a non-zero average value of the variable undergoing such dynamic hysteresis. This non-zero value indicates a breaking of symmetry of the hysteresis loop, around the origin. Such a transition to the spontaneously broken symmetric phase occurs dynamically when the driving frequency of the field increases beyond its threshold value which depends on the field amplitude and the temperature. Similar dynamic transitions also occur for pulsed and stochastically varying fields. We present an overview of the ongoing researches in this not-so-old field of dynamic hysteresis and transitions.