Date of this Version
Using an electron spin resonance spectrometer covering a wide range of frequency and magnetic field, we have measured the low-energy excitations of the S = ½ tetragonal antiferromagnets, Sr2CuO2Cl2 and Sr2Cu3O4Cl2. Our observations of in-plane energy gaps of order 0.1 meV at zero external magnetic field are consistent with a spin-wave calculation, which includes several kinds of quantum fluctuations that remove frustration. Such gaps vanish for classical spins, and were too small to be observed by other techniques. Results agree with other experiments and with exchange anisotropy parameters determined from a five-band Hubbard model.
This is an author-created, un-copyedited version of an article accepted for publication in Europhysics Letters. IOP Publishing Ltd is not responsible for any errors or omissions in this version of the manuscript or any version derived from it. The definitive publisher authenticated version is available online at dx.doi.org/10.1209/epl/i2001-00276-4.
Katsumata, K., Hagiwara, M., Honda, Z., Satooka, J., Aharony, A., Birgeneau, R. J., Chou, F., Entin-Wohlman, O., Harris, A., Kastner, M. A., Kim, Y., & Lee, Y. (2001). Direct Observation of the Quantum Energy Gap in S = ½ Tetragonal Cuprate Antiferromagnets. Europhysics Letters, 54 (4), 508-514. http://dx.doi.org/10.1209/epl/i2001-00276-4
Date Posted: 20 August 2015
This document has been peer reviewed.