Quadratic Fermi node in a 3D strongly correlated semimetal.
Quadratic Fermi node in a 3D strongly correlated semimetal.
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DOI：
10.1038/ncomms10042
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发表时间：
2015-12-07
影响因子：
16.6
通讯作者：
Shin S
中科院分区：
文献类型：
--
作者：
Kondo T;Nakayama M;Chen R;Ishikawa JJ;Moon EG;Yamamoto T;Ota Y;Malaeb W;Kanai H;Nakashima Y;Ishida Y;Yoshida R;Yamamoto H;Matsunami M;Kimura S;Inami N;Ono K;Kumigashira H;Nakatsuji S;Balents L;Shin S
强自旋轨道耦合促进了奇异的电子态，如拓扑绝缘体和超导体，但强自旋轨道和强电子-电子相互作用的结合才刚刚开始被理解。这个新兴领域的核心是5d过渡金属铱氧化物。本文采用角分辨光谱学和第一性原理计算相结合的方法，在铱酸盐Pr2Ir2O7中，我们发现了一个具有单点费米节点的非平凡态，该单点费米节点受三次对称性和时间反演对称性的保护。由于它的二次色散，在费米能量处四个简并态的独特重合，以及强库仑相互作用，我们预测了非费米液体的行为，并观察到一些证据。我们的发现表明Pr2Ir2O7是一个母态，可以被操纵来产生其他强相关的拓扑相，如拓扑Mott绝缘体、Weyl半金属、量子自旋和异常霍尔态。5d过渡金属铱酸盐为研究强自旋轨道耦合和强电子相关的联合效应提供了一个平台。在这里，作者发现Pr2Ir2O7的能带结构中存在二次带接触，这表明它可能被调谐以形成各种强相关的拓扑相。
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 5d 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. 5d transition metal iridates provide a platform to study the combined effects of strong spin orbit coupling and strong electronic correlations. Here, the authors find a quadratic band touching in the band structure of Pr2Ir2O7, suggesting it may be tuned to form various strongly correlated topological phases.