A Variable Temperature Synchrotron X-ray Diffraction Study of Colossal Magnetoresistant NdMnAsO0.95F0.05.
A Variable Temperature Synchrotron X-ray Diffraction Study of Colossal Magnetoresistant NdMnAsO0.95F0.05.
复制标题
巨色NDMNASO0.95F0.05的可变温度同步X射线衍射研究。
DOI：
10.1038/srep20705
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发表时间：
2016-02-15
影响因子：
4.6
通讯作者：
Mclaughlin AC
中科院分区：
文献类型：
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作者：
Wildman EJ;Mclaughlin AC
最近在铁砷化物中发现的高温超导电性大大促进了对过渡金属磷属元素化物的研究。最近报道了NdMnAsO 1-xFx（x = 0.05-0.08）的巨磁阻（CMR），在低温下达到最大磁阻（MR 9 T（3 K）= −95%）。这似乎是CMR的一种新机制，它是场从绝缘反铁磁体到半导体顺磁体的二级相变的结果。本文报道了CMR氧铌酸盐NdMnAsO_（0.95）F_（0.05）在4 K-290 K之间的变温同步辐射X射线粉末衍射研究。在整个温度范围内得到了与空间群为P4/nmm的四元晶胞的良好拟合，在低至4 K的温度下检测到晶体结构没有变化。的晶格和磁序的耦合进行观察，其中微妙的不连续性的温度变化的a和c/a的比率是明显的Nd自旋反铁磁性顺序和Mn的时刻重新定向到在TSR的基面。结果表明，晶格参数的微小变化会影响晶格、电子和磁性自由度之间的耦合。
The recent discovery of high temperature superconductivity in Fe arsenides has invigorated research into transition metal pnictides. Colossal magnetoresistance (CMR) has recently been reported for NdMnAsO1-xFx for x = 0.05–0.08, with a maximum magnetoresistance achieved at low temperature (MR9T(3 K)) = −95%). This appears to be a novel mechanism of CMR, which is as a result of a second order phase transition in field from an insulating antiferromagnet to a semiconducting paramagnet. Here we report a variable temperature synchrotron X-ray powder diffraction study of the CMR oxypnictide NdMnAsO0.95F0.05 between 4 K–290 K. An excellent fit to the tetragonal unit cell with space group P4/nmm is obtained over the entire temperature range, with no change in crystal structure detected down to 4 K. A coupling of the lattice and magnetic order is observed, where subtle discontinuities in the temperature variation of a and the c/a ratio are apparent as the Nd spins order antiferromagnetically and the Mn moments reorient into the basal plane at TSR. The results suggest that very small changes in lattice parameters effect the coupling between lattice, electronic and magnetic degrees of freedom.