paper

Low-Energy Excitations and Ground State Selection in Quantum Breathing Pyrochlore Antiferromagnet Ba $_{3}$ Yb $_{2}$ Zn $_{5}$ O $_{11}$

arXiv:1605.08544 · doi:10.1103/PhysRevB.93.220407

Abstract

We study low energy excitations in the quantum breathing pyrochlore antiferromagnet Ba $_{3}$ Yb $_{2}$ Zn $_{5}$ O $_{11}$ by combination of inelastic neutron scattering (INS) and thermodynamical properties measurements. The INS spectra are quantitatively explained by spin-1/2 single-tetrahedron model having $X X Z$ anisotropy and Dzyaloshinskii-Moriya interaction. This model has a two-fold 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 energy scale smaller than the instrumental resolution of INS.

5 pages 3 figures, Phys. Rev. B rapid communication in press

Low-Energy Excitations and Ground State Selection in Quantum Breathing Pyrochlore Antiferromagnet Ba3​Yb2​Zn5​O11​

Abstract

Low-Energy Excitations and Ground State Selection in Quantum Breathing Pyrochlore Antiferromagnet Ba $_{3}$ Yb $_{2}$ Zn $_{5}$ O $_{11}$