Abstract:
The structural complexity of cuprates has long made it difficult to isolate the essential ingredients for unconventional pairing in this class of high- superconductors. The infinite-layer phase provides the simplest structure for addressing this challenge, consisting only of CuO2 square planes separated by spacer ions. Remarkably, however, purely cation-substitution-based hole-doped superconductivity in this simplest limit remained unrealized for nearly four decades. At the same time, the emergence of infinite-layer nickelates has opened a new opportunity to test whether unconventional high- superconductivity beyond copper is possible and whether it follows the same underlying principles. So far, however, superconductivity in infinite-layer nickelates has appeared only at much lower temperatures than in their cuprate counterparts.
In this talk, I will present our recent progress along several fronts. First, I will discuss the realization of a hole-doped infinite-layer superconducting cuprate in chemically doped Cu (SRCO) thin films, with onset temperatures up to 100 K [1]. Hole doping is enabled by the combined effects of cation substitution and apical oxygen control. Second, by leveraging our earlier results [2,3,4] and by tuning the ionic radius of the dopant atoms, we developed a family of and realized a new superconducting infinite-layer nickelate, Ni (SECNO), with approaching 40 K [5]. I will discuss several newly emerging unconventional superconducting properties [6,7,8] in this SECNO system, along with our current understanding of their origin. The realization of hole-doped infinite-layer high- superconductivity in SRCO and SECNO demonstrates new possibilities for further enhancing superconductivity through cation-radius engineering and for bridging the physics of cuprate and nickelate superconductors. For example, understanding electron-hole symmetry in infinite-layer cuprates may shed light on the still-missing electron-doped superconductivity in nickelates.
Finally, if time allows, I will also discuss our work on clarifying long-standing controversies surrounding the chiral superconducting phase in the kagome metal Cs [9]. I will present evidence of nonreciprocal second-harmonic magnetotransport signals and a zero-field superconducting diode effect, accompanied by a pronounced reduction in the out-of-plane coherence length with decreasing thickness. These results establish kagome superconductors as a versatile platform for engineering nonreciprocal quantum devices and exploring emergent topological phases.
References:
- Jin et al. ArXiv:2605.29352 (2026)
- Zeng et al. Physical Review Letters 125, 147003 (2022)
- Zeng et al. Nature Communications 13, 743 (2022).
- Zeng et al. Science Advances 8, eabl9927 (2022).
- Chow et al. Nature 642, 58 (2025)
- Yan et al. Nature Communications 17, 6645 (2026).
- Rubi et al. Nature Communications 17, 9267 (2026).
- Grutter et al. ArXiv:2512.18005 (2026)
- Zhang et al. ArXiv:2605.29665 (2026
Professor Ariando is currently a Provost’s Chair Professor at the National University of Singapore (NUS). Concurrently, he is also a Singapore National Research Foundation (NRF) Investigator and the Deputy Head for Research and Graduate Studies of the NUS Department of Physics. His research centers on strongly correlated oxides, oxide interface physics, and two-dimensional quantum systems. Guided by a “materials-by-design” approach, he uses precise materials synthesis and interface engineering to investigate emergent quantum phenomena, including superconductivity and other exotic correlated electronic states. Over the past decade, Ariando and his team have produced a series of advances in emergent quantum states in complex oxides, oxide superconductivity, and the growth and tuning of high-quality epitaxial thin films. Beyond his research accomplishments, Ariando is also a dedicated mentor. He has trained numerous students and postdoctoral researchers who have gone on to hold independent positions at leading universities and research institutions.
