【大学频道】北京大学量子材料科学中心呈献 | 中科院高能物理研究所缪平研究员

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图 | 缪平

题   目：Large magnetovolume effect in a cobaltite perovskite

报告人：缪平

单   位：中国科学院高能物理研究所

时   间：2019-12-25

地   点：北京大学

Materials that show negative thermal expansion (NTE) have significant industrial merit because they can be used to fabricate composites whose dimensions remain invariant upon heating. In some materials, NTE is concomitant with the spontaneous magnetization due to the magnetovolume effect (MVE). Here we report a new class of MVE material; namely, a layered perovskite PrBaCo₂O_5.5+x (0 ≤ x ≤ 0.41), in which strong NTE (β ≈ -3.6×10^-5K^-1 at x = 0.24) is induced by hole doping. Furthermore, the MVE is not limited to the PrBaCo₂O_5.5+x but is also observed in the NdBaCo₂O_5.5+x. Through a comprehensive study with multiple probes (neutron, muon, electron and X-ray), we found the MVE originates from an magnetoelectric transition from an antiferromagnetic insulating large-volume (AFILV) phase to a ferromagnetic metallic small-volume (FMSV) phase.

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