Low temperature resonances in the electron heat capacity of finite systems

Temperature variations of the heat capacity (C) are studied in a low temperature regime T<δF∼εF/N for 2D and 3D systems with N∼102-104 treated as a canonical ensemble of N-noninteracting fermions. The analysis of C is performed by introducing the function φ(ε), the spectral distribution of C, that gives the contribution of each single-particle state to C. This function has two peaks divided by the energy interval Δε≈(2-5)T. If at some temperature Tres a resonance takes place i.e. the positions of these peaks coincide with energies of two levels nearest to εF then C vs T can show a local maximum at Tres. This gives us the possibility to assess the single-particle level spacings near the Fermi level.