Optical properties, electronic correlations, and Fermi surface engineering in bilayer nickelates
ORAL · Invited
Abstract
The discovery of superconductivity with TC∼80 K at ∼15 GPa in pressurized La3Ni2O7 [1] sparked considerable interest. In this presentation, I will discuss our recent advances in understanding the fundamental physics of bilayer nickelates from first principles and our efforts to achieve superconductivity at ambient pressure.
First, we explore the structural and electronic properties of A3Ni2O7 bilayer nickelates (A=La-Lu, Y, Sc) under hydrostatic pressures ranging from 0-150 GPa [2]. We compile a phase diagram from DFT+U that establishes chemical and external pressure as distinct and counteracting control parameters, in sharp contrast to the behavior observed in high-TC hydrides. Notably, Tb3Ni2O7 emerges as a promising candidate for ambient-pressure superconductivity.
Subsequently, we assess the role of electronic correlations in La3Ni2O7 by comparing experimental and simulated optical spectra [3]. We identify the optical fingerprint of the pressure-driven Fermi surface topological transition that is considered to be key for high-TC superconductivity in these systems. The impact of explicit oxygen vacancies and the optical signature of spin-density waves are addressed. Moreover, we reveal general trends in the optical response as a function of the formal Ni valence in Ruddlesden-Popper versus reduced Ruddlesden-Popper nickelates.
Finally, we investigate epitaxial strain and interface polarity as alternative strategies for tuning the Fermi surface topology in oxide heterostructures derived from bilayer nickelates. These approaches may provide pathways to realize superconductivity without external pressure [4].
[1] H. Sun et al., Nature 621, 493 (2023)
[2] B. Geisler, J. J. Hamlin, G. R. Stewart, R. G. Hennig, P. J. Hirschfeld, npj Quantum Materials 9, 38 (2024)
[3] B. Geisler, L. Fanfarillo, J. J. Hamlin, G. R. Stewart, R. G. Hennig, P. J. Hirschfeld, npj Quantum Materials 9, 89 (2024)
[4] B. Geisler, J. J. Hamlin, G. R. Stewart, R. G. Hennig, P. J. Hirschfeld, arXiv:2411.14600 [cond-mat.supr-con]
First, we explore the structural and electronic properties of A3Ni2O7 bilayer nickelates (A=La-Lu, Y, Sc) under hydrostatic pressures ranging from 0-150 GPa [2]. We compile a phase diagram from DFT+U that establishes chemical and external pressure as distinct and counteracting control parameters, in sharp contrast to the behavior observed in high-TC hydrides. Notably, Tb3Ni2O7 emerges as a promising candidate for ambient-pressure superconductivity.
Subsequently, we assess the role of electronic correlations in La3Ni2O7 by comparing experimental and simulated optical spectra [3]. We identify the optical fingerprint of the pressure-driven Fermi surface topological transition that is considered to be key for high-TC superconductivity in these systems. The impact of explicit oxygen vacancies and the optical signature of spin-density waves are addressed. Moreover, we reveal general trends in the optical response as a function of the formal Ni valence in Ruddlesden-Popper versus reduced Ruddlesden-Popper nickelates.
Finally, we investigate epitaxial strain and interface polarity as alternative strategies for tuning the Fermi surface topology in oxide heterostructures derived from bilayer nickelates. These approaches may provide pathways to realize superconductivity without external pressure [4].
[1] H. Sun et al., Nature 621, 493 (2023)
[2] B. Geisler, J. J. Hamlin, G. R. Stewart, R. G. Hennig, P. J. Hirschfeld, npj Quantum Materials 9, 38 (2024)
[3] B. Geisler, L. Fanfarillo, J. J. Hamlin, G. R. Stewart, R. G. Hennig, P. J. Hirschfeld, npj Quantum Materials 9, 89 (2024)
[4] B. Geisler, J. J. Hamlin, G. R. Stewart, R. G. Hennig, P. J. Hirschfeld, arXiv:2411.14600 [cond-mat.supr-con]
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Presenters
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Benjamin Geisler
University of Florida
Authors
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Benjamin Geisler
University of Florida
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Laura Fanfarillo
Institute of Complex Systems ISC-CNR, Istituto dei Sistemi Complessi (ISC-CNR)
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James J Hamlin
University of Florida, Department of Physics, University of Florida
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Gregory R Stewart
University of Florida, Department of Physics, University of Florida
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Richard G Hennig
University of Florida, Department of Materials Science and Engineering, University of Florida
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Peter J Hirschfeld
University of Florida, Department of Physics, University of Florida