Dirac-fermion-assisted interfacial superconductivity in epitaxial topological-insulator/iron-chalcogenide heterostructures

• Published in: Nature communications Vol. 14; no. 1; p. 7119
• Main Authors: Yi, Hemian, Hu, Lun-Hui, Zhao, Yi-Fan, Zhou, Ling-Jie, Yan, Zi-Jie, Zhang, Ruoxi, Yuan, Wei, Wang, Zihao, Wang, Ke, Hickey, Danielle Reifsnyder, Richardella, Anthony R., Singleton, John, Winter, Laurel E., Wu, Xianxin, Chan, Moses H. W., Samarth, Nitin, Liu, Chao-Xing, Chang, Cui-Zu
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 06.11.2023; Nature Publishing Group; Nature Portfolio
• Subjects: 147/143; 147/3; 639/301/357/995; 639/766/119/1003; 639/766/119/2792/4128; 639/766/119/544; 639/766/119/995; Antiferromagnetism; Antimony; Bismuth; Chemical potential; Chemical synthesis; Couplings; Electronic systems; Electrons; Fermions; Ferromagnetism; Heterostructures; Humanities and Social Sciences; Magnetic fields; Materials selection; Molecular beam epitaxy; multidisciplinary; Photoelectric emission; Photoelectron spectroscopy; Science; Science (multidisciplinary); Spectroscopic analysis; Spectroscopy; Spectrum analysis; Superconductivity; Topological insulators; Transition temperature; Transition temperatures
• ISSN: 2041-1723; 2041-1723
• DOI: 10.1038/s41467-023-42902-2

Over the last decade, the possibility of realizing topological superconductivity (TSC) has generated much excitement. TSC can be created in electronic systems where the topological and superconducting orders coexist, motivating the continued exploration of candidate material platforms to this end. Here, we use molecular beam epitaxy (MBE) to synthesize heterostructures that host emergent interfacial superconductivity when a non-superconducting antiferromagnet (FeTe) is interfaced with a topological insulator (TI) (Bi, Sb) 2 Te 3 . By performing in-vacuo angle-resolved photoemission spectroscopy (ARPES) and ex-situ electrical transport measurements, we find that the superconducting transition temperature and the upper critical magnetic field are suppressed when the chemical potential approaches the Dirac point. We provide evidence to show that the observed interfacial superconductivity and its chemical potential dependence is the result of the competition between the Ruderman-Kittel-Kasuya-Yosida-type ferromagnetic coupling mediated by Dirac surface states and antiferromagnetic exchange couplings that generate the bicollinear antiferromagnetic order in the FeTe layer. The authors study (Bi,Sb) 2 Te 3 /FeTe bilayers, which feature emergent superconductivity at the interface with T c  ~ 12 K. Through angle-resolved photoemission spectroscopy and electrical transport measurements, they argue that the Dirac-fermion-mediated Ruderman-Kittel-Kasuya-Yosida-type interaction weakens antiferromagnetic order in FeTe layer, allowing for superconductivity.