Dresden 2020 – scientific programme
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MA: Fachverband Magnetismus
MA 42: Posters Magnetism I
MA 42.48: Poster
Wednesday, March 18, 2020, 15:00–18:00, P3
Lattice effects accompanying the colossal magnetoresistance effect in HgCr2Se4 — •Steffi Hartmann1, Shuai Yang2, Yongqing Li2, Jens Müller1, and Michael Lang1 — 1Institute of Physics, Goethe-University Frankfurt, Frankfurt (Main), 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 universal occurrence of electronic and magnetic phase separation in some of these materials has led researchers to suggest a model of percolating magnetic polarons as a possible mechanism to explain 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 nano-scale magnetic clusters. 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 and a pronounced CMR effect [2]. We will discuss our results with respect to the coupling of the charge and magnetic degrees of freedom to the lattice distortion and compare our results with observations made for other CMR materials. [1] Manna et al., PRL 2014; [2] Guan et al., PRL 2015