Magnetically driven electronic phase separation in rare-earth hexaboride

The concept of magnetic polaron (MP) in condensed matter physics was introduced about four decades ago in order to understand an intriguing transport behavior of rare earth chalcogenide systems [1]. However, there is so far no comprehensive understanding of the microscopic transport mechanism of charge carriers in systems where magnetic polarons form magnetically inhomogeneous phases. Apart from several interesting spintronic materials such as dilute magnetic semiconductors, manganites, etc., new materials (e.g. several pyrochlores) have been recently discovered where the existence of MP have been suggested. Therefore, it is important to achieve a detailed understanding of the microscopic transport mechanism in such magnetically phase separated systems.

In this talk, I will discuss our recent results of fluctuation spectroscopy experiments performed on EuB6. The material shows a complex paramagnetic to ferromagnetic transition characterized by double transitions in electronic transport and thermodynamic measurements which were suggested to be related to the formation of MP. I will discuss the dynamics of MP and carriers’ charge transport behavior in such magneto-polaronic systems.

[1] S. von Molnár and S. Methfessel, J. Appl. Phys. 38, 959 (1967)