Low-temperature spin dynamics in the kagome system Pr3Ga5SiO14

Neutron-scattering measurements on a single crystal of the distorted kagome system Pr3Ga5SiO14 show that in zero magnetic field the system does not order magnetically at temperatures as low as 35 mK. The specific heat is found to exhibit T2 behavior below 4 K. These results are indicative of a low-temperature two-dimensional dynamically disordered state in this geometrically frustrated antiferromagnet. Complementary in-field NMR experiments reveal that the spins remain dynamic down to millikelvin temperatures exhibiting spin-correlation times that are field dependent. The results are consistent with a field-dependent gap in the low-energy excitation spectrum. Diffuse neutron-scattering observations suggest that the application of a magnetic field induces dynamical short-range ordering.