Orbital-Exchange and Fractional Quantum Number Excitations in an f-electron Metal Yb2Pt2Pb

Published

June 3, 2016

Author(s)

L. S. Wu, W. J. Gannon, I. A. Zaliznyak, A. M. Tsvelik, M. Brockmann, J.-S. Caux, M. S. Kim, Yiming Qiu, John R. Copley, G. Ehlers, A. Podlesnyak, M. C. Aronson

Abstract

Exotic quantum states and fractionalized magnetic excitations, such as spinons in one-dimensional chains, are generally viewed as belonging to the domain of 3d transition metal systems with spin 1/2. Our neutron scattering experiments on the 4f-electron metal Yb₂Pt₂Pb overturn this common wisdom in an unexpected and spectacular way. We observe broad magnetic continuum dispersing in only one direction, which indicates that the underlying elementary excitations are spinons carrying fractional spin-1/2. These spinons are the quantum dynamics of the anisotropic, orbital-dominated Yb moments, and thus these effective quantum spins are emergent variables that encode the electronic orbitals. The unique birthmark of their unusual origin is that only longitudinal spin fluctuations are measurable, while the transverse excitations such as spin waves are rendered wholly invisible to magnetic neutron scattering. The proliferation of these orbital-spinons strips the electrons of their orbital identity, and we thus report here a new electron fractionalization phenomenon, charge-orbital separation.

Citation

Science

Volume

353

Issue

6290

Pub Type

Journals

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Keywords

neutron scattering, orbital-spinon, charge-orbital separation

Citation

Wu, L. , Gannon, W. , Zaliznyak, I. , Tsvelik, A. , Brockmann, M. , Caux, J. , Kim, M. , Qiu, Y. , Copley, J. , Ehlers, G. , Podlesnyak, A. and Aronson, M. (2016), Orbital-Exchange and Fractional Quantum Number Excitations in an f-electron Metal Yb₂Pt₂Pb, Science, [online], https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=920050 (Accessed December 12, 2024)