在Sr 2 IrO 4和Sr 3 Ir 2 O 7中,相关性、磁性和自旋轨道耦合在类似的能量尺度上竞争,为研究金属-绝缘体转变(MIT)创造了新的背景。我们在这里使用角度分辨光电发射研究MIT作为一个功能的空穴和电子掺杂Sr 3 Ir 2 O 7,分别获得Ir/Rh和Sr/La取代。我们发现,有一个明显的减少作为掺杂的费米能级的两侧,从0.2eV到0.05eV的上下带之间的间隙的函数。虽然这两个能带在能带结构计算中具有对应物,但它们的特征在于非常不同的相干程度。上带具有清晰的准粒子峰,而下带是非常宽的,并失去重量作为掺杂的函数。此外,他们的ARPES谱权重服从不同的周期性,加强了他们的不同性质的想法。我们认为,一个非常相似的情况发生在Sr 2 IrO 4和结论,这两个家庭的物理本质上是相同的。
英文摘要:
In Sr2IrO4 and Sr3Ir2O7, correlations, magnetism and spin-orbit coupling compete on similar energy scales, creating a new context to study metal-insulator transitions (MIT). We use here Angle-Resolved photoemission to investigate the MIT as a function of hole and electron doping in Sr3Ir2O7, obtained respectively by Ir/Rh and Sr/La substitutions. We show that there is a clear reduction as a function of doping of the gap between a lower and upper band on both sides of the Fermi level, from 0.2eV to 0.05eV. Although these two bands have a counterpart in band structure calculations, they are characterized by a very different degree of coherence. The upper band exhibits clear quasiparticle peaks, while the lower band is very broad and loses weight as a function of doping. Moreover, their ARPES spectral weights obey different periodicities, reinforcing the idea of their different nature. We argue that a very similar situation occurs in Sr2IrO4 and conclude that the physics of the two families is essentially the same.
Coherent vs incoherent interlayer transport in layered metals
报道了两种准二维有机超导体的层间磁电阻随磁场、温度和角度的变化关系。对于$κ$ -(BEDT-TTF)$_2$ I $_3$,我们发现在$Θ= 90^\circ$(平行于层的场)处的角度依赖性磁阻中的良好分辨的峰。对于$β$“-(BEDT-TTF)$_2$ SF $_5$ CH $_2$ CF $_2$ SO $_3$,不存在层间输运的相干性质的这种明确证明。这和非金属行为的磁阻建议非相干准粒子运动后2D金属。
Experimental Observation of Incoherent-Coherent Crossover and Orbital Dependent Band Renormalization in Iron Chalcogenide Superconductors
电子关联水平一直是理解超导电性本质的关键问题之一。在铁基超导体中,铁硫族化合物家族表现出最强的电子关联。为了测量相关强度,我们进行了系统的角度分辨光电子能谱研究的铁硫族化物系列Fe $_{1+y}$ Se $_x$ Te $_{1-x}$(0 $<$ x $<$ 0.59),一个模型系统具有最简单的结构。我们的测量揭示了一个非相干相干交叉的电子结构中的硒比的增加和系统从弱本地化更巡回状态的演变。此外,我们发现,有效质量的带占主导地位的d $_{xy}$轨道字符显着降低,增加硒比相比,d $_{xz}$ /d $_{yz}$轨道占主导地位的频带。关联能级随轨道的变化与能带结构重正化的理论计算一致,有助于理解Fe $_{1+y}$ Se $_x$ Te $_{1-x}$的超导起始.