$d$-wave altermagnetism revealed by resonant inelastic X-ray scattering
Authors:
Guangkai Zhang,
Yuehong Li,
Xubin Ye,
Vincent C. Morano,
Sze Tung Li,
Jaewon Choi,
Rebecca Scatena,
Shuai Tang,
Maocai Pi,
Mengqi Ye,
Mirian Garcia-Fernandez,
Alessandro Bombardi,
Xiaomei Qin,
Zhao Pan,
Daniel G. Mazzone,
Qisi Wang,
Yi Lu,
Yao Shen,
Youwen Long
Abstract:
Altermagnetism defines a third fundamental class of collinear magnetic order, featuring compensated magnetic moments with antiparallel spin alignment, yet lifted Kramers degeneracy without the need for relativistic spin-orbit coupling. Its ability to host spin-polarized electronic bands and unconventional chiral magnons makes it a promising platform for functional materials. However, experimental…
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Altermagnetism defines a third fundamental class of collinear magnetic order, featuring compensated magnetic moments with antiparallel spin alignment, yet lifted Kramers degeneracy without the need for relativistic spin-orbit coupling. Its ability to host spin-polarized electronic bands and unconventional chiral magnons makes it a promising platform for functional materials. However, experimental verification has proven challenging; while circular dichroism in resonant inelastic X-ray scattering (RIXS) has been suggested as a signature of chiral magnons, it remains controversial whether this effect is an intrinsic property of altermagnetism or an artifact of experimental geometry. In this work, we resolve this debate and provide unambiguous experimental evidence of $d$-wave altermagnetism in the strongly correlated Lieb-lattice magnet La$_2$O$_3$Mn$_2$Se$_2$. The RIXS spectra exhibit a $d$-wave-symmetry circular dichroism in the magnetic excitations that vanishes in the paramagnetic phase. Through RIXS-operator symmetry analysis and exact-diagonalization calculations, we prove that the observed dichroism is a direct consequence of altermagnetic symmetry constraints, independent of magnon branch splitting. Our results provide definitive evidence for the experimental realization of $d$-wave altermagnetism in La$_2$O$_3$Mn$_2$Se$_2$ and establish circularly polarized RIXS as a highly symmetry-sensitive spectroscopic framework for detecting magnetic phases that evade conventional probes.
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Submitted 17 June, 2026;
originally announced June 2026.
Impact of Electron Correlations on Infinite-Layer Cuprates and Nickelates
Authors:
Xunyang Hong,
Yuetong Wu,
Ying Chan,
Sze Tung Li,
I. Biało,
L. Martinelli,
A. Drewanowski,
Qiang Gao,
Xiaolin Ren,
Xingjiang Zhou,
Zhihai Zhu,
A. Galdi,
D. G. Schlom,
K. M. Shen,
J. Choi,
M. Garcia Fernandez,
Ke-Jin Zhou,
N. B. Brookes,
H. M. Rønnow,
Qisi Wang,
J. Chang
Abstract:
Optimization of unconventional superconductivity involves a balance of interaction strengths. Precise determination of correlation strength across different material families is therefore important. Here, we present a combined X-ray absorption spectroscopy (XAS) and resonant inelastic X-ray scattering (RIXS) study of infinite-layer PrNiO$_2$ and SrCuO$_2$ that enables fair comparison of their inte…
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Optimization of unconventional superconductivity involves a balance of interaction strengths. Precise determination of correlation strength across different material families is therefore important. Here, we present a combined X-ray absorption spectroscopy (XAS) and resonant inelastic X-ray scattering (RIXS) study of infinite-layer PrNiO$_2$ and SrCuO$_2$ that enables fair comparison of their interaction strengths. For both compounds, we study the orbital and magnetic excitations and extract their dispersions along high-symmetry directions. Using a single-band Hubbard model and including higher-order exchange interactions, we derive the correlation factor $U/t$ for both compounds. A key finding is that despite a smaller Coulomb repulsion $U$, PrNiO$_2$ exhibits a correlation strength that is 20% stronger than that of its isostructural cuprate counterpart SrCuO$_2$. This indicates that a moderation of the correlation strength may further optimize superconductivity in nickelates.
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Submitted 12 November, 2025;
originally announced November 2025.