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Dresden 2017 – wissenschaftliches Programm

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MA: Fachverband Magnetismus

MA 66: Poster 3

MA 66.12: Poster

Freitag, 24. März 2017, 09:30–13:00, P2-OG2

Lattice effects accompanying the colossal magnetoresistance effect in HgCr2Se4 — •S. Hartmann1, E. Gati1, C. Lin2, Y. Shi2, Y. Li2, J. Müller1, and M. Lang11Physikalisches Institut, Goethe Universität, SFB/TR49, 60438 Frankfurt, Germany — 2Institute of Physics, Chinese Academy of Sciences, Beijing, China

Understanding the origin of large or colossal magnetoresistance (CMR) effects, observed in a wide range of materials, remains a challenging field of research in magnetism. The occurrence of electronic and magnetic phase separation in some of these materials has led researchers to suggest percolating magnetic polarons as one route for describing the CMR effect. In fact, studies on the semi-metallic CMR material EuB6 revealed that the magnetically-driven delocalization of charge carriers is accompanied by pronounced lattice distortions [1], consistent with the scenario of percolating magnetic polarons. With reference to these results we performed high-resolution thermal expansion and magnetostriction measurements on the half-metallic CMR material HgCr2Se4, where the paramagnetic to ferromagnetic transition at 105 K drives an insulator-to-metal transition with an 8-orders-of-magnitude decrease of the longitudinal resistivity [2]. We will discuss the phenomenology of the coupling of charge and magnetic degrees of freedom to the lattice distortion and compare our results to other CMR materials. [1] Manna et al., PRL 2014; [2] Guan et al., PRL 2015

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