Temperature dependence of the spin susceptibility of nearly ferromagnetic Fermi systems

摘要: The spin susceptibility of nearly ferromagnetic Fermi systems, e.g., liquid 3 He, Pd, Ni Ga is large (X 0 X Pauli −1 =α ≫1) and varies strongly with temperature on a scale much smaller than the temperature. A theory for this presented here. Using functional transformation, thermodynamic potential fermion system converted to that interacting fluctuations (a vector-boson field). parameters latter are determined by system. related spinfluctuation self-energy Σ. From diagrammatic analysis Σ , we show there exists convergent expansion its temperature-dependent part, in terms number correlated internal thermal fluctuations. leading have one or two fluctuations: three-spin-fluctuation term higher order Τ/α (for Τ≪ α ) Τ ≲ 1). (Here Τ=T/T F .) Thus calculation (Τ)X P =α (Τ) possible entire degenerate range 1, not merely paramagnon . α(Τ) shown go as +A(Τ 2 /α +BΤ ≲Τ≪ interpolates smoothly between these limits. (A B constants.) former paramagnon-theory result "classical" As an illustration, calculate, adjustable parameter, He 0<Τ≲0.2. agreement experiment very good.