Preparation and transport properties of high-quality thin films of the heavy-fermion system CeCu6

Thickness dependence of the ground-state properties of thin films of the heavy-fermion compoundCeCu6

“…The films are found to be homogeneous both in-plane and as a function of depth, and have sharp interfaces with substrate and protection layer. X-ray diffraction (XRD) measurements demonstrate that the films are polycrystalline (orthorhombic structure) with lattice parameters within 0.1 % of those found for bulk samples, 15 and show a slightly preferred orientation of the b-axis in growth direction. As the thickness of the films is reduced, no variations of the lattice constants, nor of the preferred orientation, are observed.…”

“…Resistance measurements were performed on structured samples in a four-probe geometry (50-200 µm wide and 2-3 mm between the voltage contacts) in applied magnetic fields up to 8 T and at temperatures down to 20 mK. We have shown in an earlier publication 15 that for a film of thickness 189 nm, the measurements of resistance versus temperature and those of the magnetoresistance mimic the properties of bulk samples, establishing the formation of a heavy Fermi-liquid state at low temperatures in such thick films.…”

“…A clear tendency toward suppression of T max is found as the thickness of the films is decreased. For d > 20 nm, Fermi-liquid behavior is found 15 at very low temperatures (T < 200 mK), ρ = ρ 0 + AT 2 , where A is the Fermi-liquid coefficient related to the effective mass m * of the quasiparticles by A ∝ (m * ) 2 . 17 The values obtained for A are shown in Fig.…”