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R. J. Spieker; B. Krohnke; D. Zhai; A. Lopez Benet; M. Spaić; X. He; C. Y. Tan; Z. W. Anderson; F. Ye; H. Cao; M. J. Krogstad; R. Osborn; D. Pelc; M. Greven

doi:10.1103/lzbm-883c

Evidence for rare-region physics in the structural and electronic degrees of freedom of the nickelate $L a_{2 - x} S r_{x} Ni O_{4}$

R. J. Spieker ¹, B. Krohnke ¹, D. Zhai ¹, A. Lopez Benet ¹, M. Spaić ², X. He ¹, C. Y. Tan ¹, Z. W. Anderson ^1,*, F. Ye ³ et al.

H. Cao ³, M. J. Krogstad ⁴, R. Osborn ⁵, D. Pelc ^1,2,†, and M. Greven ^1,‡

¹School of Physics and Astronomy, University of Minnesota, Minneapolis, Minnesota 55455, USA
²Department of Physics, Faculty of Science, University of Zagreb, 10000 Zagreb, Croatia
³Neutron Scattering Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
⁴Advanced Photon Source, Argonne National Laboratory, Lemont, Illinois 60439, USA
⁵Materials Science Division, Argonne National Laboratory, Lemont, Illinois 60439, USA

^*Present address: Materials Science Division, Argonne National Laboratory, Lemont, Illinois 60439, USA.
^†Contact author: dpelc@phy.hr
^‡Contact author: greven@umn.edu

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Phys. Rev. Materials 10, 095001 – Published 8 September, 2026

DOI: https://doi.org/10.1103/lzbm-883c

Abstract

We present a diffuse neutron and x-ray scattering study of structural as well as spin- and charge-density-wave fluctuations in the electrical insulator $L a_{2 - x} S r_{x} Ni O_{4}$ . This lamellar nickelate is an isostructural analog of the high-temperature cuprate superconductor $L a_{2 - x} S r_{x} Cu O_{4}$ , for which recent experiments uncovered evidence for unusual structural and superconducting fluctuations indicative of rare-region physics due to inherent inhomogeneity unrelated to common point disorder effects. Here we find closely analogous nanoscale orthorhombic fluctuation behavior in $L a_{2 - x} S r_{x} Ni O_{4}$ , including exponential scaling of the diffuse scattering intensity and power-law scaling of the characteristic length with relative temperature. Moreover, our neutron and x-ray scattering data reveal similar behavior for short-range magnetic and charge fluctuations above the respective ordering temperatures. These observations indicate that rare-region effects are a generic feature of perovskite-related structures and lead to universal fluctuations of both structural and electronic degrees of freedom over extended temperature ranges.

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Evidence for rare-region physics in the structural and electronic degrees of freedom of the nickelate $L a_{2 - x} S r_{x} Ni O_{4}$

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Evidence for rare-region physics in the structural and electronic degrees of freedom of the nickelate La2−xSrxNiO4

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Evidence for rare-region physics in the structural and electronic degrees of freedom of the nickelate $L a_{2 - x} S r_{x} Ni O_{4}$