Characteristic Crossing Points in Specific Heat Curves of Correlated Systems

Attention is drawn to the observation that in many correlated systems (e.g. 3He, heavy fermion systems and Hubbard models) the specific heat curves, when plotted for different values of some thermodynamic variable (e.g. pressure, magnetic field, interaction), cross almost precisely at one or two characteristic temperatures. A quantitative explanation of this phenomenon, based on the temperature dependence of the associated generalized susceptibilities, is presented. PACS: 67.55.Cx, 71.27.+a,71.28.+d In 1959 Brewer et al. [1] noticed that the specific heat curves C(T, P ) of liquid He measured at different pressures P all intersect at a temperature T+ ≃ 0.16K, and that C(T, P ) increases with increasing pressure below T+. Greywall’s high-precision measurements of the specific heat at constant volume V provided striking evidence for the sharpness of the crossing point at T+ ≃ 160mK (see Fig. 1a) [2]. At this temperature the specific heat New permanent address after September 15, 1996: Theoretische Physik III, Institut für Physik, Universität Augsburg, 86135 Augsburg, Germany; e-mail: [email protected]