Magnetically-driven electronic phase separation in the semimetallic   ferromagnet EuB$_6$
  From measurements of fluctuation spectroscopy and weak nonlinear transport on the semimetallic ferromagnet EuB$_6$ we find direct evidence for magnetically-driven electronic phase separation consistent with the picture of percolation of magnetic polarons (MP), which form highly conducting magnetically-ordered clusters in a paramagnetic and 'poorly conducting' background. These different parts of the conducting network are probed separately by the noise spectroscopy/nonlinear transport and the conventional linear resistivity. We suggest a comprehensive and 'universal' scenario for the MP percolation, which occurs at a critical magnetization either induced by ferromagnetic order at zero field or externally applied magnetic fields in the paramagentic region. 
P. Das, A. Amyan, J. Brandenburrg, J. M\"uller, P. Xiong, S. von   Moln\'ar and Z. Fisk
cond-mat.str-el cond-mat.mes-hall