The low-temperature specific heat, C(T), of the Delafossite family of triangle-planar cuprates, RCuO2+δ, has been studied for R=La and Y and 0<δ≤2/3. Structural transformations between the hexagonal and the orthorhombic phases for R=Y appear as distinct lattice-contribution changes in C(T). Near the oxygen-ordered limit, δ=2/3, C(T) displays a linear-in-T term of 6.5 and 1.3 mJ/mole K2 for R=La and Y, respectively. The large specific-heat enhancement and a similar enhancement of the magnetic susceptibility for R=La are interpreted in terms of strong correlations near a metal-antiferromagnetic-insulator instability.
All Science Journal Classification (ASJC) codes
- Condensed Matter Physics