Strong spin–orbit coupling fosters exotic electronic states such as topological insulators and superconductors, but the combination of strong spin–orbit and strong electron–electron interactions is just beginning to be understood. Central to this emerging area are the 5 d transition metal iridium oxides. Here, in the pyrochlore iridate Pr2Ir2O7, we identify a non-trivial state with a single-point Fermi node protected by cubic and time-reversal symmetries, using a combination of angle-resolved photoemission spectroscopy and first-principles calculations. Owing to its quadratic dispersion, the unique coincidence of four degenerate states at the Fermi energy, and strong Coulomb interactions, non-Fermi liquid behaviour is predicted, for which we observe some evidence. Our discovery implies that Pr2Ir2O7 is a parent state that can be manipulated to produce other strongly correlated topological phases, such as topological Mott insulator, Weyl semimetal, and quantum spin and anomalous Hall states.
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机译：强自旋轨道耦合促进了奇异的电子状态，例如拓扑绝缘体和超导体，但是强自旋轨道与强电子-电子相互作用的结合才刚刚被人们理解。该新兴区域的中心是5 d过渡金属铱氧化物。在这里，在烧绿石的铱酸盐Pr 2 Ir 2 O 7 中，我们确定了一个单点费米节点受保护的非平凡状态。使用角度分辨光发射光谱法和第一性原理计算相结合的立方和时间反转对称性。由于其二次方分散，费米能量处的四个简并态的独特重合以及强大的库仑相互作用，因此可以预测非费米液体的行为，为此我们可以观察到一些证据。我们的发现暗示Pr 2 Ir 2 O 7 是一种母体状态，可以对其进行操纵以产生其他高度相关的拓扑阶段，例如拓扑莫特绝缘子，魏尔半金属，量子自旋和异常霍尔态。
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