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arXiv 0903.5546cond-mat.supr-concond-mat.str-el
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空穴掺杂的BaFe2-xCrxAs2晶体:非超导性的一个例子

Hole-doped BaFe2-xCrxAs2 Crystals: A Case of Non-superconductivity

Athena S. Sefat, David J. Singh, Lindsay H. VanBebber, Michael A. McGuire, Yurij Mozharivskyj, Rongying Jin, Brian C. Sales, Veerle Keppens, David Mandrus

摘要:

研究了Cr掺杂BaFe_2As_2的砷化铁层的物理性质和电子结构。这种形式的空穴掺杂导致对BaFe 2-xCrxAs 2(x > 0)中的磁性/结构相变的抑制,但不导致超导性。对于不同的x值,电阻率,比热,磁化率,霍尔系数,和单晶X射线衍射数据的温度依赖性。这些材料显示出接近铁磁状态的特征,包括x低至0.36的变磁转变,增强的磁化率和大的索末菲系数。这样的结果反映了由于自旋涨落的重正化,并且在x = 1时得到密度泛函计算的支持。计算结果表明,Fe和Cr的磁有序性和化学有序性之间存在很强的相互作用,具有铁磁性的基态。这种铁磁基态解释的电子结构。由此产生的相图是暗示,超导性并不简单地来自抑制的结构/磁性转变。

英文摘要:

We investigate the physical properties and electronic structure upon Cr-doping in the iron arsenide layers of BaFe2As2. This form of hole-doping leads to suppression of the magnetic/structural phase transition in BaFe2-xCrxAs2 for x > 0, but does not lead to superconductivity. For various x values, temperature dependence of the resistivity, specific heat, magnetic susceptibility, Hall coefficient, and single crystal x-ray diffraction data are presented. The materials show signatures of approaching a ferromagnetic state with x, including a metamagnetic transition for x as little as 0.36, an enhanced magnetic susceptibility, and a large Sommerfeld coefficient. Such results reflect renormalization due to spin fluctuations and they are supported by density functional calculations at x = 1. Calculations show a strong interplay between magnetic ordering and chemical ordering of Fe and Cr, with a ferromagnetic ground state. This ferromagnetic ground state is explained in terms of the electronic structure. The resulting phase diagram is suggestive that superconductivity does not derive simply from the suppression of the structural/magnetic transitions.

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