Department of Applied Physics, Stanford University1
Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory2
Ever since their discovery, superconductivity in cuprates has motivated the search for materials with analogous electronic or atomic structure. Here we present how soft chemistry approaches can be used to synthesize superconducting infinite layer nickelates from their perovskite precursor phase, using topotactic reactions [1,2]. We will present the synthesis and transport properties of the nickelate superconductors, and our current understanding of aspects of the electronic structure, including the unusual role of rare-earth hybridization [3,4]. A particular focus will be on the observation of a doping-dependent superconducting dome in (Nd,Sr)NiO2, similar to cuprates [5]. However, while cuprate superconductivity is bounded by an insulator for underdoping and a metal for overdoping, here we observe weakly insulating behavior on either side of the dome. Furthermore, the normal state Hall coefficient is always small and proximate to a continuous zero crossing in doping and in temperature, in contrast to the ~1/x dependence observed for cuprates. This suggests the presence of both electron- and hole-like bands, consistent with band structure calculations. Finally, the recent observation of superconductivity in (Pr,Sr)NiO2 suggests that the possibility of a broad family of nickelate superconductors, as found in cuprates and pnictides [6].
[1] D. F. Li, K. Lee, B. Y. Wang, M. Osada, S. Crossley, H. R. Lee, Y. Cui, Y. Hikita, and H. Y. Hwang, Nature 572, 624 (2019).
[2] K. Lee, B. H. Goodge, D. F. Li, M. Osada, B. Y. Wang, Y. Cui, L. F. Kourkoutis, and H. Y. Hwang, APL Materials 8, 041107 (2020).
[3] M. Hepting, D. Li, C. J. Jia, H. Lu, E. Paris, Y. Tseng, X. Feng, M. Osada, E. Been, Y. Hikita, Y.-D. Chuang, Z. Hussain, K. J. Zhou, A. Nag, M. Garcia-Fernandez, M. Rossi, H. Y. Huang, D. J. Huang, Z. X. Shen, T. Schmitt, H. Y. Hwang, B. Moritz, J. Zaanen, T. P. Devereaux, and W. S. Lee, Nature Materials 19, 381 (2020).
[4] B. H. Goodge, D. F. Li, M. Osada, B. Y. Wang, K. Lee, G. A. Sawatzky, H. Y. Hwang, and L. F. Kourkoutis, arXiv:2005.02847.
[5] D. F. Li, B. Y. Wang, K. Lee, S. P. Harvey, M. Osada, B. H. Goodge, L. F. Kourkoutis, and H. Y. Hwang, Physical Review Letters 125, 027001 (2020).
[6] M. Osada, B. Y. Wang, B. H. Goodge, K. Lee, H. Yoon, K. Sakuma, D. F. Li, M. Miura, L. F. Kourkoutis, and H. Y. Hwang, Nano Letters 20, 5735 (2020).