Lattice strain accompanying the colossal magnetoresistance effect in EuB${}_6$

Abstract

The coupling of magnetic and electronic degrees of freedom to the crystal lattice in the ferromagnetic semimetal EuB${}_6$, which exhibits a complex ferromagnetic order and a colossal magnetoresistance (CMR) effect, %, very likely involving magnetic polarons, is studied by high-resolution thermal expansion and magnetostriction experiments. EuB${}_6$ may be viewed as a model system, where pure magnetism-tuned transport and the response of the crystal lattice can be studied in a comparatively simple environment,i.e., not influenced by strong crystal-electric field effects and Jahn-Teller distortions. We find a very large lattice response, quantified by (i) the magnetic Grüneisen parameter, (ii) the spontaneous strain when entering the ferromagnetic region and (iii) the magnetostriction in the paramagnetic temperature regime. Our analysis reveals that a significant part of the lattice effects originates in the magnetically-driven delocalization of charge carriers, consistent with the scenario of percolating magnetic polarons. A strong effect of the formation and dynamics of local magnetic clusters on the lattice parameters is suggested to be a general feature of CMR materials.

5 pages and 3 figures

References in corpus (4)

• Anomalous Lattice Response at the Mott Transition in a Quasi-2D Organic Conductor
• Nonlinear Hall effect as a signature of electronic phase separation in the semimetallic ferromagnet EuB6
• Magnetically-driven electronic phase separation in the semimetallic ferromagnet EuB${}_6$
• Possible magnetic-polaron-switched positive and negative magnetoresistance in the GdSi single crystal

Cited by in corpus (4)

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