Inverted hysterons and hysteresis branch crossings: New ideas in modelling hysteresis*

For nearly 100 years, it has been assumed that the ascending and descending branches of a magnetization hysteresis loop cannot cross. This assumption was largely based on the erroneous conclusion that the region of the crossed branches violates conservation of energy. It has recently been shown that the hysteresis branch crossing (HBC) is a real, reproducible, and robust phenomenon which violates no fundamental law. The existence of the HBC raises several interesting and fundamental questions about the way hysteresis has been modelled and the assumptions of various mathematical models of hysteresis; in particular, the Preisach model.

  In this talk, both experimental evidence and theoretical arguments supporting the existence of the hysteresis branch crossing will be presented. These ideas reveal the fact that a serious flaw exists in the way the Laws of Thermodynamics have been applied to hysteresis modelling. Additionally, these ideas reveal the need to consider “inverted hysterons” in both the classical Preisach model and the nonlinear Preisach model. The implications and nature of the inverted hysteron will be discussed.