Neutron scattering study in breathing pyrochlore antiferromagnet Ba3Yb2Zn5O11

Comprehensive study on breathing pyrochlore antiferromagnet Ba3Yb2Zn5O11 [1] is presented. To identify the energy scheme of crystalline electric field (CEF), we performed inelastic neutron scattering (INS) measurement in high energy range. The observed dispersionless excitations are explained by a CEF Hamiltonian of Kramers ion Yb3+ of which the local symmetry exhibits C3v point group symmetry. The magnetic susceptibility is consistently reproduced by the energy scheme of the CEF excitations. To identify the spin Hamiltonian we performed INS experiment in low energy range and thermodynamic property measurements at low temperatures. The INS spectra are quantitatively explained by spin-1/2 single-tetrahedron model having XXZ anisotropy and Dzyaloshinskii-Moriya interaction. This model has a two-fold degeneracy of the lowest-energy state per tetrahedron and well reproduces the magnetization curveat 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 energy scale smaller than the instrumental resolution of INS. Possible mechanisms for the ground state selection are discussed [2].
Pyrochlore, Antiferromagnetism, Electric fields, Neutron diffraction, Magnetic susceptibility, Thermodynamic properties
Masuda, T., Haku , T., Soda, M., Sera, M., Kimura, K., Taylor, J., Itoh, S., Yokoo, T., Matsumoto, Y., Yu, D., Mole, R. A., Takeuchi, T., Nakatsuji, S., Kohno, Y., Sakakibara, T., & Chang, L.-J. (2017). Neutron scattering study in breathing pyrochlore antiferromagnet Ba3Yb2Zn5O11. Paper presented at ICNS 2017 (International Conference on Neutron Scattering), Daejeon, South Korea, 9 to 13 July 2017. Retrieved from: