DOE OSTI · 3012246
Spectrally sharp magnetic excitations above the critical temperature in a frustrated Weyl semimetal
Abstract
The rare-earth α-pyrochlore iridates are a prospective class of conducting frustrated magnets where electronic correlations, large spin-orbit coupling, and geometrical frustration interplay, leading to a rich set of magnetic and electronic phases. Despite their intriguing properties, the magnetic order and excitations in this fundamental class of topological quantum materials remain poorly understood due to challenges in growing large single crystals and insufficient microscopic information on their temperature-dependent phases. Here, by combining state-of-the-art thin-film synthesis, resonant elastic and inelastic X-ray scattering, spin wave analysis, and dynamical spin susceptibility calculations, we unequivocally reveal the presence of spectrally sharp, gapped magnetic excitations in Y 2 Ir 2 O 7 that surprisingly persist well above the Néel transition temperature, signaling the presence of a quasi-universal regime connected to fluctuations on frustrated lattices. This finding implies the existence of a highly unusual cooperative paramagnetic (CP) phase above the ordering temperature and offers an explanation for the puzzling high-temperature magnetic behavior observed across the family of metallic pyrochlore crystals. Understanding such magnetic excitations at technologically relevant temperatures opens up possibilities for novel topological spintronic devices.
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Terilli, Michael [Rutgers University, Piscataway, NJ (United States)] (ORCID:0000000303618642), Jia, Xun [Argonne National Laboratory (ANL), Argonne, IL (United States); Chinese Academy of Sciences, Beijing (China)] (ORCID:0000000234464570), Liu, Xiaoran [Rutgers University, Piscataway, NJ (United States); Chinese Academy of Sciences, Beijing (China)] (ORCID:0000000309386109), Laurell, Pontus [University of Tennessee, Knoxville, TN (United States)] (ORCID:0000000235254145), Nedić, Ana-Marija [University of Minnesota, Minneapolis, MN (United States)] (ORCID:0000000188405747), Chang, Yueqing [Rutgers University, Piscataway, NJ (United States)] (ORCID:0000000200691708), Wu, Tsung-Chi [Rutgers University, Piscataway, NJ (United States)], Chen, Huyongqing [Boston University, MA (United States)], Li, Hongze [University of Texas at Austin, TX (United States)] (ORCID:000000023017383X), Upton, Mary H. [Argonne National Laboratory (ANL), Argonne, IL (United States)], Kim, Jungho [Argonne National Laboratory (ANL), Argonne, IL (United States)], Kim, Jong-Woo [Argonne National Laboratory (ANL), Argonne, IL (United States)] (ORCID:0000000196412947), Ryan, Philip J. [Argonne National Laboratory (ANL), Argonne, IL (United States)] (ORCID:000000015247349X), Nelson, Christie [Brookhaven National Laboratory (BNL), Upton, NY (United States)] (ORCID:0000000201960340), Zhou, Jianshi [University of Texas at Austin, TX (United States)], Kareev, Mikhail [Rutgers University, Piscataway, NJ (United States)], Hu, Wanzheng [Boston University, MA (United States)] (ORCID:0000000209260760), Pixley, Jedediah H. [Rutgers University, Piscataway, NJ (United States); Flatiron Institute, New York, NY (United States)] (ORCID:000000023109640X), Fiete, Gregory A. [Northeastern University, Boston, MA (United States); Massachusetts Institute of Technology, Cambridge, MA (United States)] (ORCID:0000000194770804), Cao, Yue [Argonne National Laboratory (ANL), Argonne, IL (United States); University of Chicago, IL (United States)] (ORCID:000000023989158X), Chakhalian, Jak [Rutgers University, Piscataway, NJ (United States)] (ORCID:0000000181689441). 2025-07-17. Spectrally sharp magnetic excitations above the critical temperature in a frustrated Weyl semimetal. https://doi.org/10.1038/s41467-025-61752-8
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