Figure 4: Differential heat capacity measurement in La1.675Eu0.2Sr0.125CuO4.
From: Unconventional charge order in a co-doped high-Tc superconductor

Two features can be discerned—the orthorhombic-tetragonal structural transition at TLTT∼130 K and a signature of the intermediate phase at TEN. The latter is strong evidence that a true thermodynamic phase transition takes place close to TEN. Inset shows a comparison between the quadrupolar correlation function |σ3|(kT)3 (circles; error bars are s.d. from measurements at different electric fields) and ΔCp (small circles) for temperatures in the vicinity of TEN. The ΔCp measurement in the inset is performed ∼10 times slower than in the main graph, enhancing the sharpness of the cusp at TEN. The solid line is a fit to a logarithmic divergence ln|(T−TEN)/TEN|, showing that no simple power law (scaling) relation can describe the data.