  The A-site ordered chromate spinels LiGa1-xInxCr4O8 host a network of
size-alternating spin-3/2 Cr3+ tetrahedra known as a 'breathing' pyrochlore
lattice. For the x=0.05 composition, the complex magneto-structural ordering
observed in the parent x=0 material is replaced by a single transition at Tf=11
K, ascribed to the collinear nematic order caused by strong spin-lattice
coupling. We present here an inelastic neutron scattering study of the spin
dynamics in this composition. Above Tf , the dynamical scattering function
S(Q,E) is ungapped and quasi-elastic, similar to undoped LiGaCr4O8. Below Tf ,
the spectral weight splits between a broad inelastic feature at 5.8 meV and
toward the elastic line. The former feature can be ascribed to spin precessions
within antiferromagnetic loops, lifted to finite energy by the effective
biquadratic spin-lattice term in the spin Hamiltonian.
