Low-energy excitations and ground-state selection in the quantum breathing pyrochlore antiferromagnet Ba3Yb2Zn5O11

We study low-energy excitations in the quantum breathing pyrochlore antiferromagnet Ba3Yb2Zn5O11 by a combination of inelastic neutron scattering (INS) and thermodynamical property measurements. The INS spectra are quantitatively explained by spin-12 single-tetrahedron model having XXZ anisotropy and Dzyaloshinskii-Moriya interactions. This model has a twofold degeneracy of the lowest-energy state per tetrahedron and well reproduces the magnetization curve at 0.5 K and heat capacity above 1.5 K. At lower temperatures, however, we observe a broad maximum in the heat capacity around 63 mK, demonstrating that a unique quantum ground state is selected due to extra perturbations with an energy scale smaller than the instrumental resolution of INS. ©2024 American Physical Society. All rights reserved.

Keywords

Pyrochlore, Antiferromagnetism, Ground states, Zinc, Ytterbium, Barium, Neutron diffraction

Citation

Haku, T., Kimura, K., Matsumoto, Y., Soda, M., Sera, M., Yu, D., Mole, R. A., Takeuchi, T., Nakatsuji, S., Kono, Y., Sakakibara, T., Chang, L. J., & Masuda, T. (2016). Low-energy excitations and ground-state selection in the quantum breathing pyrochlore antiferromagnet Ba3Yb2Zn5O11. Physical Review B, 93(22), 220407. doi:10.1103/PhysRevB.93.220407