Temperature Dependence of the Spin Susceptibility of a Nearly Ferromagnetic Fermi Liquid

Béal-Monod, M. T.; Ma, Shang‐keng; Fredkin, D. R.

doi:10.1103/physrevlett.20.929

Cited by 221 publications

(110 citation statements)

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“…For interacting fermions, γ(T ) is not an analytic function of T 2 ; the leading temperature dependence is instead proportional to T 2 ln(T ) in three dimensions (3D) and T in 2D The T 2 ln T term was first found by Eliashberg in a theoretical study of electrons interacting with acoustic phonons [5], and the possibility of a nonanalytic temperature dependence of γ was subsequently (but apparently independently) inferred from measurements of γ for 3 He by Abel, Wheately and Andersen [1]. The 3 He measurements led to a large literature [4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,25,26,27,28,29,30] which we review in detail below. We note here a few crucial (and seemingly contradictory) results.…”

Section: Introductionmentioning

confidence: 99%

“…The thermodynamic properties of itinerant fermionic systems is a subject of long-standing experimental [1,2,3] and theoretical [4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,25,26,27,28,29,30] interest. It is generally accepted [31,32] that the low-temperature behavior of a wide class of interacting fermionic systems is controlled by the Fermi-liquid fixed point.…”

Section: Introductionmentioning

confidence: 99%

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Nonanalytic corrections to the specific heat of a three-dimensional Fermi liquid

2006

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We revisit the issue of the leading nonanalytic corrections to the temperature dependence of the specific heat coefficient, γ(T ) = C(T )/T, for a system of interacting fermions in three dimensions. We show that the leading temperature dependence of the specific heat coefficient γ(T ) − γ(0) ∝ T 3 ln T comes from two physically distinct processes. The first process involves a thermal excitation of a single particle-hole pair, whose components interact via a nonanalytic dynamic vertex. The second process involves an excitation of three particle-hole pairs which interact via the analytic static fixed-point vertex. We show that the single-pair contribution is expressed via the backscattering amplitude of quasiparticles at the Fermi surface. The three-pair contribution does not have a simple expression in terms of scattering in particular directions. We clarify the relation between these results and previous literature on both 3D and 2D systems, and discuss the relation between the nonanalyticities in γ and those in spin susceptibilities.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Nonanalytic corrections to the specific heat of a three-dimensional Fermi liquid

2006

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“…At finite temperatures, the principal correction term to the constant is a ϪT 2 term, which in the paramagnon model is reinforced by low-energy spin fluctuations ͑paramagnons͒. 48 For temperatures above 0.2 K, even stronger deviations are observed.…”

Section: B Magnetic Susceptibilitymentioning

confidence: 99%

Effective mass, spin fluctuations, and zero sound in liquid3He

et al. 2000

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We have measured and calculated the density and spin-density dynamic structure factors S c (Q, ) and S I (Q, ) of normal liquid 3 He as a function of wave vector Q and temperature T. The static spin susceptibility (T) and specific heat C V (T) are also calculated. These properties all depend upon the effective mass m*(k, ) of the Fermi quasiparticles making up the liquid. We use a model in which m* peaks near the Fermi surface to m*ϭ2.8, the Landau theory effective mass, and decreases toward the bare mass m*ϭ1 for quasiparticles away from the Fermi energy ⑀ F . The theory for all the properties may be viewed as Landau theory with an effective mass m*(⑀ k )ϭm*(k) that decreases as the quasiparticle energy ⑀ k moves away from ⑀ F . The peaking of m* at ⑀ F is widely predicted in Fermi systems and the aim is to test how important this physical feature is in the dynamics of liquid 3 He. We find that S c (Q, ) and S I (Q, ) versus Q and T as well as (T) are well reproduced by the model for the same m*(k). The C V (T) can be reproduced, but a much lower value of m*(k) at energies ⑀ k away from ⑀ F is required, m*Ӎ0.5, as found in previous calculations of C V (T). We conclude that the peaking of m* at ⑀ F is an important physical feature to include in calculations of S (Q, ) and that the quasiparticle model itself is inadequate for C V at higher temperatures.

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“…(2) that the deviation from the linear dependence of C(T )/T on T 2 is due to the temperature dependence of λ sf . Moreover, Béal-Monod, Ma, and Fredkin [25] have estimated the shift δC/T caused by an applied field H to be…”

Section: Figmentioning

confidence: 99%

Competition between BCS superconductivity and ferromagnetic spin fluctuations inMgCNi3

et al. 2005

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The low temperature specific heat of the superconductor MgCNi3 and a non-superconductor MgC0.85Ni3 is investigated in detail. An additional contribution is observed from the data of MgCNi3 but absent in MgC0.85Ni3, which is demonstrated to be insensitive to the applied magnetic field even up to 12 Tesla. A detailed discussion on its origin is then presented. By subtracting this additional contribution, the zero field specific heat of MgCNi3 can be well described by the BCS theory with the gap ratio (∆/kBTc ) determined by the previous tunneling measurements. The conventional s-wave pairing state is further proved by the magnetic field dependence of the specific heat at low temperatures and the behavior of the upper critical field.PACS numbers: 74.25. Bt, 74.20.Rp, 74.70.Ad Since the discovery of the new intermetalic perovskite superconductor MgCNi 3 [1], plenty of efforts have been focused on the superconducting pairing symmetry in this material because its conduction electrons are derived predominantly from Ni which is itself a ferromagnet [2,3,4,5]. However, up to now, there is still not a consensus on this issue. The measured penetration depth [6], critical current behavior [7] and earlier tunneling spectra [8] suggested an unconventional superconductivity, the later tunneling data [9] supported the s-wave pairing symmetry and gave a reasonable interpretation on the contradiction to the result in Ref [8]. The s-wave pairing has also been demonstrated by the 13 C NMR experiments [10] and the specific heat measurements [1,8,11,12,13,14]. To our knowledge, all the previous reports on the specific heat of MgCNi 3 [1,8,11,12,13,14] were characterized in the framework of a conventional phonon-mediated pairing. However, there is an obvious deviation of the experimental data from the prediction of BCS theory in the low temperature [8,15], i.e., the entropy conservation rule is not satisfied. Such deviation has been interpreted by the presence of unreacted Ni impurities in Refs [8,15], whereas it is still prominent in the samples without Ni impurities [14]. On the other hand, strong spin fluctuations have been observed in MgCNi 3 by NMR experiment [10], which is suggested to be able to severely affect the superconductivity in MgCNi 3 [2,5,10,11,16] or even induce some exotic paring mechanism [2]. Consequently, the behavior of the specific heat will inevitably be changed by the spin fluctuations. Therefore, before a real pairing mechanism being concluded from the specific heat data, we have to carefully investigate how the ferromagnetic spin fluctuations contribute to the specific heat of MgCNi 3 .In this work, we elaborate on the specific heat (C) of MgC x Ni 3 system both in normal state and supercon- * Electronic address: hhwen@aphy.iphy.ac.cn ducting state. A low temperature upturn is clearly distinguished in the C/T vs T 2 curves and found to be insensitive to the applied magnetic field. By doing some quantitative analysis, we present the evidence of most possible mechanisms responsible for this upturn. After s...

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Temperature Dependence of the Spin Susceptibility of a Nearly Ferromagnetic Fermi Liquid

Cited by 221 publications

References 6 publications

Nonanalytic corrections to the specific heat of a three-dimensional Fermi liquid

Nonanalytic corrections to the specific heat of a three-dimensional Fermi liquid

Effective mass, spin fluctuations, and zero sound in liquid3He

Competition between BCS superconductivity and ferromagnetic spin fluctuations inMgCNi3

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