Using electron spin resonance (ESR), a well-defined breather excitation was observed in a very wide-field range for Cu benzoate exposed to a staggered field. The field dependence of the energy gap showed good agreement with the results of previously reported specific-heat measurements. Overall, the results establish the validity of the mass formula of the uniform first-breather mode at q = 0 in a wide-field range for a quantum SG system.
All Science Journal Classification (ASJC) codes
- Physics and Astronomy(all)