James C. McGroddy Prize for New Materials (2021): A sixteen-barrel atomic launcher — homing in on new materials and novel physics*

Three decades ago, Jim Eckstein started experimenting with atomic-layer-by-layer molecular-beam epitaxy (ALL-MBE) of cuprates. Darrell Schlom and I joined, and despite widespread skepticism, soon we were growing films showing high-temperature superconductivity (HTS), and a little later, new “artificial” (metastable) HTS materials such as Bi₂Sr₂Ca_n-1Cu_nO_2n+2 with n = 4, 5,…,8,…, as well as atomically-precise heterostructures and superlattices.
In the years since, the technique has matured; we constructed 2^nd and 3^rd generation systems that integrate ALL-MBE with advanced surface-science tools such as LEEM, LEISS, ARPES, and STM. We learned how to utilize the epitaxial strain and epitaxial stabilization, delta-doping, interfacial charge transfer (aka “doping without disorder”), and proximity effects. We synthesized new metastable materials such as perovskite SrMnO₃ (it’s stable structure is hexagonal), Ba₃LaBi₂O₉, L_2-xSr_xNiO₄, with 0 ≤ x ≤1.4, etc.
The study of these unique samples sparked the discovery of new phenomena — electron pairing well outside the superconducting region (of doping, temperature, and energy); interfacial superconductivity; giant proximity effect; electronic nematicity, etc. — painting a new picture of HTS in cuprates. [1]
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