论文标题
轨道选择性超导体fe $ _ {1+y} $ te $ _ {1-x} $ se $ _ {x} $
Nematic Fluctuations in an Orbital Selective Superconductor Fe$_{1+y}$Te$_{1-x}$Se$_{x}$
论文作者
论文摘要
我们介绍了一项系统的研究，该研究对使用弹药疗法技术的硫代基化超导体超导体fe $ _ {1+y} $ te $ _ {1-x} $ _ {1-x} $ _ {x} $（$ 0 \ leq x \ leq x \ leq 0.53 $）。接近$ x = 0 $，靠近fe $ _ {1+y} $ te的双条纹磁性顺序，观察到$ b_ {1g} $ nematic敏感性。在增加$ x $的情况下，尽管没有磁性顺序，$ b_ {2g} $ nematic敏感性会增加并占主导地位，紧随$（π，π）$旋转波动的强度。在各种成分（$ 0.17 \ leq x \ leq 0.53 $）中，而$ b_ {2g} $ nematic敏感性遵循低温下的居里温度依赖性（weiss温度为零），它显示出与高于50k $ $ 50k $的温度的偏差。这与在典型的pnictides中观察到的相反，在典型的铁菌群中，在低温下看到库里 - 韦斯偏差。我们将这种不寻常的温度依赖性归因于$ d_ {xy} $ orbital的相干性的丧失，这是由我们的理论计算支持的。我们的结果突出了轨道分化对铁基材料的列表特性的重要性。
We present a systematic study of the nematic fluctuations in the iron chalcogenide superconductor Fe$_{1+y}$Te$_{1-x}$Se$_{x}$ ($0 \leq x \leq 0.53$) using the elastoresistivity technique. Near $x = 0$, in proximity to the double-stripe magnetic order of Fe$_{1+y}$Te, a diverging $B_{1g}$ nematic susceptibility is observed. Upon increasing $x$, despite the absence of magnetic order, the $B_{2g}$ nematic susceptibility increases and becomes dominant, closely following the strength of the $(π, π)$ spin fluctuations. Over a wide range of compositions ($0.17 \leq x \leq 0.53$), while the $B_{2g}$ nematic susceptibility follows a Curie temperature dependence (with zero Weiss temperature) at low temperatures, it shows deviations from Curie-Weiss behavior for temperatures higher than $50K$. This is the opposite of what is observed in typical iron pnictides, where Curie-Weiss deviations are seen at low temperatures. We attribute this unusual temperature dependence to a loss of coherence of the $d_{xy}$ orbital, which is supported by our theoretical calculations. Our results highlight the importance of orbital differentiation on the nematic properties of iron-based materials.
