Elementary excitations of an S=1/2 antiferromagnetic Heisenberg chain KCuGaF 6 were investigated through specific heat and electron spin resonance (ESR) measurements. In this compound, a staggered field is induced perpendicular to the external field because of the alternating g tensor and the Dzyaloshinsky-Moriya interaction with an alternating D vector. Such a spin system can be mapped onto the quantum sine-Gordon (SG) model, when subjected to the external magnetic field. Specific heat shows clear evidence of the field-induced gap, which is related to the elementary excitations, solitons and breathers, characteristic of the quantum SG model. q=0 excitations originated from solitons and breathers were directly observed by high-frequency high-field ESR. These experimental results are well described by the quantum SG field theory.
Physica E Low-Dimensional Systems and Nanostructures
- Pub Date:
- January 2011
- Condensed Matter - Strongly Correlated Electrons
- 7 pages, 9 figures, to appear in Physica E (proceedings of International Symposium on Nanoscience and Quantum Physics nanoPHYS'09)