Magnetic susceptibility and electron–phonon (e–p) interaction in some U and Ce based heavy fermion (HF) systems

Abstract Here an attempt is made to explore the variation of magnetic susceptibility with temperature for different values of the position of f-level (d) and electron–phonon interaction (EPI) strength (r) in some U and Ce based heavy Fermion (HF) systems within Periodic Anderson Model (PAM) in the presence of a static magnetic field B and interaction of phonons with electrons of hybridization band. Since magnetic susceptibility χ is related to the f-electron occupation n ± σ f , the expression for the latter is analytically derived through f–f correlation function following the Green function technique of Zubarev. The numerical analysis of χ as a function of temperature ‘T’ is done for different values of d and r. The results show a good agreement with the experiments for some U and Ce based HFs. An explanation for the existence of a critical value of d w.r.t. EF for switching of nature of χ∼T from U to Ce based HF systems is provided. Our calculated value of the temperature Tχmax corresponding to the peak position of χ for small values of hybridization constant γ=0.002 and 0.0036 coincides with the experimental value of 19 K for UPt3 and 35 K for UPd2Al3 reported by Frings et al. and Geibel et al. respectively.