# Distinct spinon and holon dispersions in photoemission spectral functions from one-dimensional SrCuO2

## Abstract

Spin and charge are inseparable traits of an electron, but in one-dimensional solids, theory predicts their separation into collective modes—as independent excitation quanta (or particles) called spinons and holons. Experimentalists have long sought to verify this effect. Angle-resolved photoemission (ARPES) should provide the most direct evidence of spin–charge separation, as the single quasiparticle peak splits into a spinon–holon two-peak-like structure. Despite extensive ARPES experiments, the unambiguous observation of the two-peak structure has remained elusive. Here we report ARPES data from SrCuO2, made possible by recent technological developments, that unequivocally show the spinon–holon two-peak structure and their distinct dispersions. The spinon and holon branches are found to have energy scales of 0.43 and 1.3 eV, respectively, which are in quantitative agreement with the theoretical predictions.

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## Acknowledgements

This work is supported (in part) by the Korea Science and Engineering Foundation through the Center for Strongly Correlated Materials Research. Z.-X.S. acknowledges support from DOE contract DE-FG03-01ER45929-A001. ALS is operated by the DOE's Office of BES, Division of Materials Science, under Contract No. DE-AC03-76SF00098.

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Correspondence to B. J. Kim or C. Kim.

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The authors declare no competing financial interests.

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Kim, B., Koh, H., Rotenberg, E. et al. Distinct spinon and holon dispersions in photoemission spectral functions from one-dimensional SrCuO2. Nature Phys 2, 397–401 (2006). https://doi.org/10.1038/nphys316

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