Thermal conductivity of the kagome antiferromagnet herbertsmithite
ORAL
Abstract
As a close realization of the S = 1/2 kagome Heisenberg antiferromagnet, herbertsmithite (ZnCu3(OH)6Cl2) is an emblematic quantum spin liquid candidate. We have measured the thermal conductivity of several protonated and deuterated single crystals of herbertsmithite, over a wide range of temperature (0.05 – 120 K) and magnetic field (0 – 15 T).
While the thermal conductivity is found to be independent of field above T = 15 K, we uncover two field-dependent regimes at lower temperatures. For 2 ≤ T ≤ 15 K, the thermal conductivity increases monotonically with the magnetic field. For T ≤ 2K, the field dependence is non monotonic and reaches a maximum value around 10 T. There is no residual linear term in the T = 0 limit, consistent with the absence of fermionic spinons.
We attribute the thermal conductivity mostly to phonons, most likely scattered by impurity spins, and discuss the possibility of a contribution from itinerant spin excitations.
While the thermal conductivity is found to be independent of field above T = 15 K, we uncover two field-dependent regimes at lower temperatures. For 2 ≤ T ≤ 15 K, the thermal conductivity increases monotonically with the magnetic field. For T ≤ 2K, the field dependence is non monotonic and reaches a maximum value around 10 T. There is no residual linear term in the T = 0 limit, consistent with the absence of fermionic spinons.
We attribute the thermal conductivity mostly to phonons, most likely scattered by impurity spins, and discuss the possibility of a contribution from itinerant spin excitations.
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Presenters
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Etienne Lefrancois
- Universite de Sherbrooke
- Université de Sherbooke
- Université de Sherbrooke