Craco Luis, Leoni Stefano
Instituto de Física, Universidade Federal de Mato Grosso, Cuiabá, MT, 78060-900, Brazil.
School of Chemistry, Cardiff University, Cardiff, CF10 3AT, UK.
Sci Rep. 2017 Apr 18;7:46439. doi: 10.1038/srep46439.
Transport properties of tetragonal iron monosulfide, mackinawite, show a range of complex features. Semiconductive behavior and proximity to metallic states with nodal superconductivity mark this d-band system as unconventional quantum material. Here, we use the density functional dynamical mean-field theory (DFDMFT) scheme to comprehensively explain why tetragonal FeS shows both semiconducting and metallic responses in contrast to tetragonal FeSe which is a pseudogaped metal above the superconducting transition temperature. Within local-density-approximation plus dynamical mean-field theory (LDA+DMFT) we characterize its paramagnetic insulating and metallic phases, showing the proximity of mackinawite to selective Mott localization. We report the coexistence of pseudogaped and anisotropic Dirac-like electronic dispersion at the border of the Mott transition. These findings announce a new understanding of many-particle physics in quantum materials with coexisting Dirac-fermions and pseudogaped electronic states at low energies. Based on our results we propose that in electron-doped FeS substantial changes would be seen when the metallic regime was tuned towards an electronic state that hosts unconventional superconductivity.
四方晶系的单硫化铁（硫铁矿）的输运性质呈现出一系列复杂的特征。半导体行为以及与具有节点超导性的金属态的接近程度，使得这个d带系统成为一种非常规量子材料。在此，我们使用密度泛函动态平均场理论（DFDMFT）方案，全面解释为什么四方晶系的FeS与四方晶系的FeSe形成对比，FeSe在超导转变温度以上是一种赝能隙金属，而四方晶系的FeS既表现出半导体响应又表现出金属响应。在局域密度近似加动态平均场理论（LDA + DMFT）框架内，我们对其顺磁绝缘相和金属相进行了表征，表明硫铁矿接近选择性莫特局域化。我们报告了在莫特转变边界处赝能隙和各向异性狄拉克型电子色散的共存。这些发现为量子材料中的多粒子物理带来了新的理解，其中在低能量下存在共存的狄拉克费米子和赝能隙电子态。基于我们的结果，我们提出在电子掺杂的FeS中，当金属态朝着承载非常规超导性的电子态调整时，将会观察到实质性的变化。
