标题： Eu5In2As6中的两种具有不同机制的巨大磁阻效应 显示英文标题

标题： Two types of colossal magnetoresistance with distinct mechanisms in Eu5In2As6

摘要： 最近关于几种磁性半金属和半导体中巨大负磁阻（CMR）的报道引起了关注，因为这些材料缺乏传统的CMR机制，如混合价态、双交换相互作用和Jahn-Teller畸变。因此，已经提出了新的机制，包括拓扑能带结构、铁磁团簇、轨道电流和电荷有序。这些化合物中的CMR已被报道有两种形式：要么是电阻率峰，要么是被磁场抑制的电阻率上升。在这里，我们在一种反铁磁半导体Eu5In2As6中揭示了这两种类型的CMR。通过输运和热力学测量，我们证明峰型CMR可能是由于磁极子的渗流随磁场增加所致，而上升型CMR则可能是由于磁场下电荷有序的熔化所致。我们认为其他化合物中也存在类似的机制，为理解看似不同的材料中的CMR提供了一个统一的框架。 显示英文摘要

摘要： Recent reports of colossal negative magnetoresistance (CMR) in a few magnetic semimetals and semiconductors have attracted attention, because these materials are devoid of the conventional mechanisms of CMR such as mixed valence, double exchange interaction, and Jahn-Teller distortion. New mechanisms have thus been proposed, including topological band structure, ferromagnetic clusters, orbital currents, and charge ordering. The CMR in these compounds has been reported in two forms: either a resistivity peak or a resistivity upturn suppressed by a magnetic field. Here we reveal both types of CMR in a single antiferromagnetic semiconductor Eu5In2As6. Using the transport and thermodynamic measurements, we demonstrate that the peak-type CMR is likely due to the percolation of magnetic polarons with increasing magnetic field, while the upturn-type CMR is proposed to result from the melting of a charge order under the magnetic field. We argue that similar mechanisms operate in other compounds, offering a unifying framework to understand CMR in seemingly different materials.