Berlin 2015 – wissenschaftliches Programm
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MA: Fachverband Magnetismus
MA 39: Spin-dependent Transport Phenomena I
MA 39.8: Vortrag
Donnerstag, 19. März 2015, 11:15–11:30, H 0112
Lattice strain accompanying the colossal magnetoresistance effect in EuB6 — •Rudra Sekhar Manna1, 2, Pintu Das1, Mariano de Souza1, Frank Schnelle1, Michael Lang1, Stephan von Molnár3, Zachary Fisk4, and Jens Müller1 — 1Phys. Inst., Goethe-University Frankfurt, 60438 Frankfurt (Main), SFB/TR49, Germany — 2EP VI, EKM, Augsburg University, 86159 Augsburg, Germany — 3Phys. Dept., FSU, Tallahassee, Florida 32306, USA — 4Phys. Dept., UC Irvine, California 92697, USA
Semimetallic EuB6 shows a complex ferromagnetic order and a colossal magnetoresistance effect due to the interplay of magnetic, electronic and lattice degrees of freedom. EuB6 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 performed thermal expansion and magnetostriction measurements and find a large lattice response when the system enters the ferromagnetic region. Our analysis reveals that a significant part of these lattice effects - quantified by the large magnetic Grüneisen parameter and spontaneous strain when entering the ferromagnetic region - 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 colossal magnetoresistance materials [1].
[1] R. S. Manna et al., PRL 113, 067202 (2014)