Lattice Strain Accompanying the Colossal Magnetoresistance Effect in EuB6
Lattice Strain Accompanying the Colossal Magnetoresistance Effect in EuB6
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DOI：
10.1103/physrevlett.113.067202
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发表时间：
2014-08-05
影响因子：
8.6
通讯作者：
Fisk, Zachary
中科院分区：
文献类型：
--
作者：
Manna, Rudra Sekhar;Das, Pintu;Fisk, Zachary
采用高分辨率的热膨胀和磁致伸缩实验，研究了具有复杂铁磁有序和巨大磁阻效应的铁磁半金属EuB6中，磁性和电子自由度与晶格的耦合。EuB6可以看作是一个模型系统，在相对简单的环境中，即不受强晶体电场效应和扬-泰勒扭曲的影响，可以研究纯磁调谐输运和晶格的响应。我们发现了一个非常大的晶格响应，通过(i)磁性Gruneisen参数，（ii）进入铁磁区域时的自发应变，以及（iii）顺磁温度状态下的磁致伸缩来量化。我们的分析表明，晶格效应的很大一部分源于电荷载流子的磁驱动离域，这与渗透磁极化子的情况一致。局部磁团簇的形成和动力学对晶格参数的强烈影响是巨磁阻材料的一个普遍特征。
The coupling of magnetic and electronic degrees of freedom to the crystal lattice in the ferromagnetic semimetal EuB6, which exhibits a complex ferromagnetic order and a colossal magnetoresistance effect, is studied by high-resolution thermal expansion and magnetostriction experiments. 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 find a very large lattice response, quantified by (i) the magnetic Gruneisen parameter, (ii) the spontaneous strain when entering the ferromagnetic region, and (iii) the magnetostriction in the paramagnetic temperature regime. Our analysis reveals that a significant part of the lattice effects 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.