Mishra, S. G. ; Ramakrishnan, T. V.
(1978)
*Temperature dependence of the spin susceptibility of nearly ferromagnetic Fermi systems*
Physical Review B: Condensed Matter and Materials Physics, 18
(5).
pp. 2308-2317.
ISSN 1098-0121

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Official URL: http://prb.aps.org/abstract/PRB/v18/i5/p2308_1

Related URL: http://dx.doi.org/10.1103/PhysRevB.18.2308

## Abstract

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

Item Type: | Article |
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Source: | Copyright of this article belongs to The American Physical Society. |

ID Code: | 40815 |

Deposited On: | 25 May 2011 11:00 |

Last Modified: | 25 May 2011 11:00 |

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