Spin-Induced Optical Conductivity in the Spin-Liquid Candidate Herbertsmithite
Abstract
We report a direct measurement of the low-frequency optical conductivity of large-area single-crystal herbertsmithite, a promising spin-liquid candidate material, by means of terahertz time-domain spectroscopy. In the spectral range below 1.4 THz, we observe a contribution to the real part of the in-plane conductivity σab(ω) from the spin degree of freedom. This spin-induced conductivity exhibits a power-law dependence on frequency σab(ω)∼ωβ with β≈1.4. Our observation is consistent with the theoretically predicted low-frequency conductivity arising from an emergent gauge field of a gapless U(1) Dirac spin liquid.
- Publication:
-
Physical Review Letters
- Pub Date:
- September 2013
- DOI:
- 10.1103/PhysRevLett.111.127401
- arXiv:
- arXiv:1301.3501
- Bibcode:
- 2013PhRvL.111l7401P
- Keywords:
-
- 78.20.-e;
- 75.10.Kt;
- 78.30.-j;
- Optical properties of bulk materials and thin films;
- Infrared and Raman spectra;
- Condensed Matter - Strongly Correlated Electrons
- E-Print:
- 9 pages, 6 figures (supplementary information included)