Measuring small changes in calorimetric properties using a ’’direct difference’’ technique

Abstract
A simple method is described for determining small changes in calorimetric properties when an external field is applied, without the use of curve fitting or other interpolation schemes. This is illustrated using recent data for strong‐coupling superconductors, in which the changes in the electronic specific heat, entropy, and free energy between the normal and superconducting states are to a large extent obscured by the common lattice contribution. In the same context, errors introduced by thermometer magnetoresistance at low fields are discussed, and a new technique for determining the magnetoresistance correction is presented.