Thermal Hall Effect of Spin Excitations in a Kagome Magnet
Author(s)Hirschberger, Max; Chisnell, Robin; Lee, Young S.; Ong, N. P.
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At low temperatures, the thermal conductivity of spin excitations in a magnetic insulator can exceed that of phonons. However, because they are charge neutral, the spin waves are not expected to display a thermal Hall effect. However, in the kagome lattice, theory predicts that the Berry curvature leads to a thermal Hall conductivity κ[subscript xy]. Here we report observation of a large κ[subscript xy] in the kagome magnet Cu(1-3, bdc) which orders magnetically at 1.8 K. The observed κ[subscript xy] undergoes a remarkable sign reversal with changes in temperature or magnetic field, associated with sign alternation of the Chern flux between magnon bands. The close correlation between κ[subscript xy] and κ[subscript xx] firmly precludes a phonon origin for the thermal Hall effect.
DepartmentMassachusetts Institute of Technology. Department of Physics
Physical Review Letters
American Physical Society
Hirschberger, Max, Robin Chisnell, Young S. Lee, and N. P. Ong. “Thermal Hall Effect of Spin Excitations in a Kagome Magnet.” Physical Review Letters 115, no. 10 (September 2015). © 2015 American Physical Society
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