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Direct Observation of the Quantum Energy Gap in S = 1/2 Tetragonal Cuprate Antiferromagnets

K. Katsumata·M. Hagiwara·Z. Honda·J. Satooka·Amnon Aharony·R. J. Birgeneau·F. C. Chou·O. Entin-Wohlman·A. B. Harris·M. A. Kastner·Y. J. Kim·Y. S. Lee
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Abstract

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=1/2 tetragonal antiferromagnets, Sr_{2}CuO_{2}Cl_{2} and Sr_{2}Cu_{3}O_{4}Cl_{2}. Our observation 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. Results agree with other experiments and with exchange anisotropy parameters determined from a five band Hubbard model.

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K. Katsumata, M. Hagiwara, Z. Honda, J. Satooka, Amnon Aharony, R. J. Birgeneau, F. C. Chou, O. Entin-Wohlman, A. B. Harris, M. A. Kastner, Y. J. Kim, Y. S. Lee. 2000-08-01. Direct Observation of the Quantum Energy Gap in S = 1/2 Tetragonal Cuprate Antiferromagnets. https://doi.org/10.1209/epl%2Fi2001-00276-4

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