  A unified thermodynamic framework for characterization of functional
materials is developed. This framework encompasses linear reversible and
irreversible processes with thermal, electrical, magnetic, and/or mechanical
effects coupled. The comprehensive framework combines the principles of
classical equilibrium and non-equilibrium thermodynamics with electrodynamics
of continua in the infinitesimal strain regime.
  In the first part of this paper, linear Thermo-Electro-Magneto-Mechanical
(TEMM) quasistatic processes are characterized. Thermodynamic stability
conditions are further imposed on the linear constitutive model and
restrictions on the corresponding material constants are derived. The framework
is then extended to irreversible transport phenomena including thermoelectric,
thermomagnetic and the state-of-the-art spintronic and spin caloritronic
effects. Using Onsager's reciprocity relationships and the dissipation
inequality, restrictions on the kinetic coefficients corresponding to charge,
heat and spin transport processes are derived. All the constitutive models are
accompanied by multiphysics interaction diagrams that highlight the various
processes that can be characterized using this framework.
