该研究团队利用扫描隧道光谱技术研究了化合物4Hb-TaS2，该化合物交织了1T-TaS2的莫特绝缘态和假定自旋液体，以及2H-TaS2的金属态和低温超导相。研究人员揭示了一个热力学相图，展示了相关的类近藤团簇态和耗尽的平带态之间的一阶量子相变。研究人员证明了这种内在相变可以通过电场、温度以及操纵与探针尖端的层间耦合来诱导，从而允许在类近藤团簇和耗尽的平带状态之间可逆地切换。相变表现为全电子谱的不连续变化，并伴有迟滞和低频噪声。他们发现相图中过渡线的形状取决于两个电子态的局部可压缩性和熵。这一研究发现为系统研究和操纵莫特-金属相变以及其中的强相关相和量子相变提供了一个令人兴奋的平台。
据悉，将不同的相关和拓扑上不平凡的物质电子相耦合在一起，可以潜在地诱导出新的电子序和相变。过渡金属二硫族化合物是探索这类杂化体系的基础，它们展现出各种奇异的电子相。由于其范德华性质，这些化合物可以通过剥离和堆叠或化学计量生长进行掺杂，从而诱导出新的相关复合物。
附：英文原文
Title: First-order quantum phase transition in the hybrid metal–Mott insulator transition metal dichalcogenide 4Hb-TaS2
Author: Kumar Nayak, Abhay, Steinbok, Aviram, Roet, Yotam, Koo, Jahyun, Feldman, Irena, Almoalem, Avior, Kanigel, Amit, Yan, Binghai, Rosch, Achim, Avraham, Nurit, Beidenkopf, Haim
Issue&Volume: 2023-10-19
Abstract: Coupling together distinct correlated and topologically nontrivial electronic phases of matter can potentially induce novel electronic orders and phase transitions among them. Transition metal dichalcogenide compounds serve as a bedrock for exploration of such hybrid systems. They host a variety of exotic electronic phases, and their Van der Waals nature enables to admix them, either by exfoliation and stacking or by stoichiometric growth, and thereby induce novel correlated complexes. Here, we investigate the compound 4Hb-TaS2 that interleaves the Mott-insulating state of 1T-TaS2 and the putative spin liquid it hosts together with the metallic state of 2H-TaS2 and the low-temperature superconducting phase it harbors using scanning tunneling spectroscopy. We reveal a thermodynamic phase diagram that hosts a first-order quantum phase transition between a correlated Kondo-like cluster state and a depleted flat band state. We demonstrate that this intrinsic transition can be induced by an electric field and temperature as well as by manipulation of the interlayer coupling with the probe tip, hence allowing to reversibly toggle between the Kondo-like cluster and the depleted flat band states. The phase transition is manifested by a discontinuous change of the complete electronic spectrum accompanied by hysteresis and low-frequency noise. We find that the shape of the transition line in the phase diagram is determined by the local compressibility and the entropy of the two electronic states. Our findings set such heterogeneous structures as an exciting platform for systematic investigation and manipulation of Mott–metal transitions and strongly correlated phases and quantum phase transitions therein.
DOI: 10.1073/pnas.2304274120
Source: https://www.pnas.org/doi/abs/10.1073/pnas.2304274120