A Generalized Presentation of Multi-caloric Effects Based on Exterior Derivative Theory and its Applications

The emerging concept of multicaloric effects, introduced in 2010, entails the application of multiple interplay fields to a thermodynamic system. While multicaloric effects are main focus of experimental endeavors, theoretical considerations fall short of providing a thorough understanding. This paper introduces a comprehensive presentation on multicaloric effects, employing the method and theory of exterior derivative formations. It addresses every aspects of thermodynamic systems, showcasing its applicability to multicaloric materials (both single-phase and multi-phase materials), and its adaptability to different scenarios (either a single or multiple force fields). The formulation of Maxwell relationships, characterized by their generality and universality, enables a clear prediction in entropy and temperature, facilitating a distinct identification between independent and interdependent contributions from multicaloric effects.These insights hold significant importance in designing and developing specialized thermodynamic materials, optimizing functional performances and exploring innovative mechanisms.