Quantum criticality in electron-doped BaFe2−xNixAs2
Quantum criticality in electron-doped BaFe2−xNixAs2
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DOI：
10.1038/ncomms3265
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发表时间：
2013-08
影响因子：
16.6
通讯作者：
R. Zhou;Zong-Rui Li;Jiyong Yang;D. Sun;Chengtian T. Lin;G. Zheng;G. Zheng
中科院分区：
文献类型：
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作者：
R. Zhou;Zong-Rui Li;Jiyong Yang;D. Sun;Chengtian T. Lin;G. Zheng;G. Zheng
量子临界点是系统相图中的一个点，在绝对零度（T）下，该点处的阶数被完全抑制。量子临界点的存在在有限T物理性质中表现出来，并且经常引起新的物质状态。铜氧化物和重费米子材料中的超导性被许多人认为是由与量子临界点相关的波动介导的。在最近发现的铁磷属元素化物超导体中，我们报告了BaFe 2 − xNixAs 2（0≤x≤0.17）的输运和NMR测量。在xc1 =0.10和xc2 =0.14处发现两个临界点。电阻率服从ρ=ρ0+ Δ Tn，其中在xc1附近n =1，在xc2处n =1.1。通过核磁共振测量，我们确定xc 1是一个磁量子临界点，并提出xc 2是一个与磁结构相变有关的新的量子临界点。我们的结果表明，载流子掺杂磷属化合物的超导电性与量子临界性密切相关。
A quantum critical point is a point in a system’s phase diagram at which an order is completely suppressed at absolute zero temperature (T). The presence of a quantum critical point manifests itself in the finite-Tphysical properties, and often gives rise to new states of matter. Superconductivity in the cuprates and in heavy fermion materials is believed by many to be mediated by fluctuations associated with a quantum critical point. In the recently discovered iron–pnictide superconductors, we report transport and NMR measurements on BaFe2−xNixAs2(0≤x≤0.17). We find two critical points atxc1=0.10 andxc2=0.14. The electrical resistivity followsρ=ρ0+ATn, withn=1 aroundxc1and another minimaln=1.1 atxc2. By NMR measurements, we identityxc1to be a magnetic quantum critical point and suggest thatxc2is a new type of quantum critical point associated with a nematic structural phase transition. Our results suggest that the superconductivity in carrier-doped pnictides is closely linked to the quantum criticality.