Absence of colossal magnetoresistance in the oxypnictide PrMnAsO0.95F0.05.
Absence of colossal magnetoresistance in the oxypnictide PrMnAsO0.95F0.05.
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DOI：
10.1021/ic502445t
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发表时间：
2015-02
影响因子：
4.6
通讯作者：
E. Wildman;F. Sher;A. Mclaughlin
中科院分区：
文献类型：
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作者：
E. Wildman;F. Sher;A. Mclaughlin
我们最近报道了一种新的电子掺杂锰氧化物NdMnAsO1-xFx的巨磁电阻(CMR)机制。在3K时，磁阻高达-95%。在这里，我们展示了当将ND替换为Pr时，令人惊讶的是CMR不再存在。相反，PrMnAsO0.95F0.05在35K以下观察到相当大的负磁电阻(PrMnAsO0.95F0.05的MR7T(12K)=-13.4%)。对PrMnAsO0.95F0.05进行了详细的中子和同步辐射X射线衍射研究，结果表明，在35K时，发生了从四方P4/NMM到正交PmMn的结构转变。结构转变是由Pr4f电子自由度驱动的。下面观察到的较大的MR很可能是由于施加磁场时磁和/或多极散射的减少而产生的。
We have recently reported a new mechanism of colossal magnetoresistance (CMR) in electron doped manganese oxypnictides NdMnAsO1-xFx. Magnetoresistances of up to -95% at 3 K have been observed. Here we show that upon replacing Nd for Pr, the CMR is surprisingly no longer present. Instead a sizable negative magnetoresistance is observed for PrMnAsO0.95F0.05 below 35 K (MR7T (12 K) = -13.4% for PrMnAsO0.95F0.05). A detailed neutron and synchrotron X-ray diffraction study of PrMnAsO0.95F0.05 has been performed, which shows that a structural transition, Ts, occurs at 35 K from tetragonal P4/nmm to orthorhombic Pmmn symmetry. The structural transition is driven by the Pr 4f electrons degrees of freedom. The sizable -MR observed below the transition most likely arises due to a reduction in magnetic and/or multipolar scattering upon application of a magnetic field.