A quantum spin liquid (QSL) is an exotic state of matter in which electrons’ spins are quantum entangled over long distances, but do not show magnetic order in the zero-temperature limit. The observation of QSL states is a central aim of experimental physics, because they host collective excitations that transcend our knowledge of quantum matter; however, examples in real materials are scarce. We report neutron-scattering experiments on YbMgGaO4, a QSL candidate in which Yb3+ ions with effective spin-1/2 occupy a triangular lattice. Furthermore, our measurements reveal a continuum of magnetic excitations—the essential experimental hallmark of a QSL7—at very low temperature (0.06 K). The origin of this peculiar excitation spectrum is a crucial question, because isotropic nearest-neighbour interactions do not yield a QSL ground state on the triangular lattice. In using measurements the field-polarized state, we identify antiferromagnetic next-nearest-neighbour interactions spin-space anisotropies and chemical disorder between the magnetic layers as key ingredients in YbMgGaO4.
Paddison, Joseph A. M., et al. "Continuous excitations of the triangular-lattice quantum spin liquid YbMgGaO<sub>4</sub>." Nature Physics, vol. 13, no. 2, Dec. 2016. https://doi.org/10.1038/nphys3971
@article{osti_1361300,
author = {Paddison, Joseph A. M. and Daum, Marcus and Dun, Zhiling and Ehlers, Georg and Liu, Yaohua and Stone, Matthew B. and Zhou, Haidong and Mourigal, Martin},
title = {Continuous excitations of the triangular-lattice quantum spin liquid YbMgGaO<sub>4</sub>},
annote = {A quantum spin liquid (QSL) is an exotic state of matter in which electrons’ spins are quantum entangled over long distances, but do not show magnetic order in the zero-temperature limit. The observation of QSL states is a central aim of experimental physics, because they host collective excitations that transcend our knowledge of quantum matter; however, examples in real materials are scarce. We report neutron-scattering experiments on YbMgGaO4, a QSL candidate in which Yb3+ ions with effective spin-1/2 occupy a triangular lattice. Furthermore, our measurements reveal a continuum of magnetic excitations—the essential experimental hallmark of a QSL7—at very low temperature (0.06 K). The origin of this peculiar excitation spectrum is a crucial question, because isotropic nearest-neighbour interactions do not yield a QSL ground state on the triangular lattice. In using measurements the field-polarized state, we identify antiferromagnetic next-nearest-neighbour interactions spin-space anisotropies and chemical disorder between the magnetic layers as key ingredients in YbMgGaO4.},
doi = {10.1038/nphys3971},
url = {https://www.osti.gov/biblio/1361300},
journal = {Nature Physics},
issn = {ISSN 1745-2473},
number = {2},
volume = {13},
place = {United States},
publisher = {Nature Publishing Group (NPG)},
year = {2016},
month = {12}}
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