Abstract:
Materials are found in multiple phases in the nature. A typical example
is water, which is commonly seen in solid, liquid and vapor phases. Various
equilibrium phases are decided by thermodynamic parameters like temperature
(T), pressure (P), magnetic field (h), etc. A phase transition [1–4]
occurs whenever the system undergoes a change from one equilibrium phase
to another with the variation of these parameters. Phase transition is also
observed in collective behavior of biological entities [5, 6]. Here, unlike inanimate
or “passive” objects, system constituents are self propelled. This type
of systems are called the “active” matter to distinguish them from the standard
“passive” cases. In active matter transitions, usually a steady state is
the counterpart of above mentioned equilibrium state. Large portion of this
thesis deals with the passive systems. Therefore, unless mentioned explicitly,
we will refer to a “passive system” simply as a “system”.
