Speaker: Michael R. Norman, Argonne Distinguished Fellow / Director, Argonne Quantum Institute

Host: Chandan Setty

Title: Cuprates and Nickelates and More Nickelates, Oh My

Abstract: The discovery of cuprate superconductivity in 1986 led soon afterwards to speculations of whether high temperature superconductivity existed in other transition metal oxides, in particular low valence (d^9-d) nickelates.  In 2019, this was discovered in the infinite-layer nickelate Sr-doped NdNiO₂.  But four years later, a surprising discovery was made of high temperature superconductivity under pressure in two layered (d^7+d) nickelates, La₃Ni₂O₇ and La₄Ni₃O₁₀, followed by a subsequent discovery at ambient pressure in strained films.  In this talk, I will review what we know about these two classes of nickelates and their similarities and differences with cuprates.  A focus will be on the relation of superconductivity to the charge and spin density waves found in these materials, and the contrasting contributions of dx²-y² and dz² nickel orbitals.

Bio: Michael Norman is in the Materials Science Division at Argonne and is an Argonne Distinguished Fellow and also the director of the Argonne Quantum Institute. He is a Fellow of the American Physical Society and received the John Bardeen Prize in 2026.  His research interests include superconductivity, magnetism, spin liquids, quantum criticality, and the interpretation of spectroscopic data in correlated electron materials.