  Several heavy-fermion metals display a quantum phase transition from an
antiferromagnetic metal to a heavy Fermi liquid. In some materials, however,
recent experiments seem to find that the heavy Fermi liquid phase can be
directly tuned into a non-Fermi liquid phase without apparent magnetic order.
We analyze a candidate state for this scenario where the local moment system
forms a spin liquid with gapless fermionic excitations. We discuss the thermal
conductivity and spin susceptibility of this fractionalized state both in two
and, in particular, three spatial dimensions for different temperature regimes.
We derive a variational functional for the thermal conductivity and solve it
with a variational ansatz dictated by Keldysh formalism. In sufficiently clean
samples and for an appropriate temperature window, we find that thermal
transport is dominated by the spinon contribution which can be detected by a
characteristic maximum in the Wiedemann-Franz ratio. For the spin
susceptibility, the conduction electron Pauli paramagnetism is much smaller
than the spinon contribution whose temperature dependence in three dimensions
is logarithmically enhanced as compared to the Fermi liquid result.
