  Recently a new class of quantum magnets, the so-called breathing pyrochlore
spin systems, have attracted much attention due to their potential to host
exotic emergent phenomena. Here, we present magnetometry, heat capacity,
thermal conductivity, Muon-spin relaxation, and polarized inelastic neutron
scattering measurements performed on high-quality single-crystal samples of
breathing pyrochlore compound Ba3Yb2Zn5O11. We interpret these results using a
simplified toy model and provide a new insight into the low-energy physics of
this system beyond the single-tetrahedron physics proposed previously.
