Abstract :

In this talk I will explain the phenomenology of the quantum phase transition in ferromagnetic metals, which commonly display a first-order transition at low temperatures, with a tricritical point and associated tricritical wings in the phase diagram, see the phase diagram of UGe2 shown below. After a general introduction to quantum phase transitions, I will show that the Third Law of Thermodynamics puts constraints on the phase diagram of such systems: The coexistence curve in zero field necessarily has an infinite slope at zero temperature, and the tricritical wings are perpendicular to the zero-temperature plane, but not to the zero-field plane. These results, which are based on the third law and basic thermodynamics only, explain existing data for many systems.

ABOUT THE SPEAKER:

Prof. Dietrich Belitz is a condensed matter theoretical physicist specializing in quantum many body systems. He received his PhD in 1982 from the Technical University of Munich, Germany, where he remained as postdoctoral researcher until 1985. He then moved to the US, first to the University of Maryland before joining the faculty at the University of Oregon in 1987, where he is currently the Director of the Institute of Theoretical Science. He is the author of over 120 publications and has been an invited speaker at many conferences. He is a Fellow of the American Physical Society.