The relationship between spin fluctuations and electronic heat capacity in La2-xSrxCuO4

When the electronic heat capacity of the high temperature superconductor La2-xSrxCuO4 is measured as a function of doping at its transition temperature, it is found to be peaked a critical value p=0.24. This suggests that there is a quantum critical point (QCP) at this composition. Here we propose to make detailed measurements of the spin excitations at the same temperature for two compositions to determine whether the peak and the underlying QCP can be understood in terms of spin fluctuations. Our results could demonstrate the spin excitations dominate the electronic thermal thermodynamic properties, which would have important consequences for the theory of cuprate superconductivity.