Signatures for spinons in the quantum spin liquid candidate ${\mathrm{Ca}}_{10}{\mathrm{Cr}}_{7}{\mathrm{O}}_{28}$
Abstract
We present new experimental lowtemperature heat capacity and detailed dynamical spinstructure factor data for the quantum spinliquid candidate material ${\mathrm{Ca}}_{10}{\mathrm{Cr}}_{7}{\mathrm{O}}_{28}$. The measured heat capacity shows an almostperfect linear temperature dependence in the range $0.1K ≲T≲ 0.5K$, reminiscent of fermionic spinon degrees of freedom. The spinstructure factor exhibits two energy regimes of strong signal which display rather different but solely diffuse scattering features. We theoretically describe these findings by an effective spinonhopping model which crucially relies on the existence of strong ferromagnetically coupled triangles in the system. Our spinon theory is shown to naturally reproduce the overall weight distribution of the measured spinstructure factor. Particularly, we argue that various different observed characteristic properties of the spinstructure factor and the heat capacity consistently indicate the existence of a spinon Fermi surface. A closer analysis of the heat capacity at the lowest accessible temperatures hints toward the presence of weak fwave spinonpairing terms inducing a small partial gap along the Fermi surface (except for discrete nodal Dirac points) and suggesting an overall Z2 quantum spinliquid scenario for ${\mathrm{Ca}}_{10}{\mathrm{Cr}}_{7}{\mathrm{O}}_{28}$.
 Authors:

 Freie Univ., Berlin (Germany); HelmholtzZentrum Berlin (HZB), (Germany). German Research Centre for Materials and Energy
 Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
 Goethe Univ., Frankfurt (Germany)
 HelmholtzZentrum Berlin (HZB), (Germany). German Research Centre for Materials and Energy
 National Inst. of Standards and Technology (NIST), Boulder, CO (United States); Univ. of Maryland, College Park, MD (United States)
 HelmholtzZentrum Berlin (HZB), (Germany). German Research Centre for Materials and Energy; Technische Univ. Berlin (Germany)
 Publication Date:
 Research Org.:
 Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
 Sponsoring Org.:
 USDOE Office of Science (SC), Basic Energy Sciences (BES)
 OSTI Identifier:
 1607143
 Grant/Contract Number:
 AC0500OR22725
 Resource Type:
 Accepted Manuscript
 Journal Name:
 Physical Review B
 Additional Journal Information:
 Journal Volume: 100; Journal Issue: 17; Journal ID: ISSN 24699950
 Publisher:
 American Physical Society (APS)
 Country of Publication:
 United States
 Language:
 English
 Subject:
 75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; Quantum spin liquid; Specific heat; Spinon; Heisenberg model; Mean field theory; Neutron scattering
Citation Formats
Sonnenschein, Jonas, Balz, Christian, Tutsch, Ulrich, Lang, Michael, Ryll, Hanjo, RodriguezRivera, Jose A., Islam, A. T. M. Nazmul, Lake, Bella, and Reuther, Johannes. Signatures for spinons in the quantum spin liquid candidate Ca10Cr7O28. United States: N. p., 2019.
Web. doi:10.1103/PhysRevB.100.174428.
Sonnenschein, Jonas, Balz, Christian, Tutsch, Ulrich, Lang, Michael, Ryll, Hanjo, RodriguezRivera, Jose A., Islam, A. T. M. Nazmul, Lake, Bella, & Reuther, Johannes. Signatures for spinons in the quantum spin liquid candidate Ca10Cr7O28. United States. doi:https://doi.org/10.1103/PhysRevB.100.174428
Sonnenschein, Jonas, Balz, Christian, Tutsch, Ulrich, Lang, Michael, Ryll, Hanjo, RodriguezRivera, Jose A., Islam, A. T. M. Nazmul, Lake, Bella, and Reuther, Johannes. Mon .
"Signatures for spinons in the quantum spin liquid candidate Ca10Cr7O28". United States. doi:https://doi.org/10.1103/PhysRevB.100.174428. https://www.osti.gov/servlets/purl/1607143.
@article{osti_1607143,
title = {Signatures for spinons in the quantum spin liquid candidate Ca10Cr7O28},
author = {Sonnenschein, Jonas and Balz, Christian and Tutsch, Ulrich and Lang, Michael and Ryll, Hanjo and RodriguezRivera, Jose A. and Islam, A. T. M. Nazmul and Lake, Bella and Reuther, Johannes},
abstractNote = {We present new experimental lowtemperature heat capacity and detailed dynamical spinstructure factor data for the quantum spinliquid candidate material Ca10Cr7O28. The measured heat capacity shows an almostperfect linear temperature dependence in the range $0.1K ≲T≲ 0.5K$, reminiscent of fermionic spinon degrees of freedom. The spinstructure factor exhibits two energy regimes of strong signal which display rather different but solely diffuse scattering features. We theoretically describe these findings by an effective spinonhopping model which crucially relies on the existence of strong ferromagnetically coupled triangles in the system. Our spinon theory is shown to naturally reproduce the overall weight distribution of the measured spinstructure factor. Particularly, we argue that various different observed characteristic properties of the spinstructure factor and the heat capacity consistently indicate the existence of a spinon Fermi surface. A closer analysis of the heat capacity at the lowest accessible temperatures hints toward the presence of weak fwave spinonpairing terms inducing a small partial gap along the Fermi surface (except for discrete nodal Dirac points) and suggesting an overall Z2 quantum spinliquid scenario for Ca10Cr7O28.},
doi = {10.1103/PhysRevB.100.174428},
journal = {Physical Review B},
number = 17,
volume = 100,
place = {United States},
year = {2019},
month = {11}
}
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