Anomalous scaling behavior of the dynamical spin susceptibility ofCe0.925La0.075Ru2<

Abstract

Inelastic neutron scattering measurements have been performed on single crystals of the heavy fermion compound Ce0.925La0.075Ru2Si2 in broad energy [0.1, 9.5 meV] and temperature [40 mK, 294 K] ranges in order to address the question of scaling behavior of the dynamical spin susceptibility at the quantum critical point of an itinerant magnetic system. For two wavevectors Q corresponding to uncorrelated and antiferromagnetically correlated spin fluctuations, it is found that the dynamical spin susceptibility χ ′′ (Q, E, T ) is independent of temperature below a cut-off temperature TQ: the spin fluctuation amplitude saturates at low temperatures contrarily to its expected divergence at a quantum critical point. Above TQ, a Q-dependent scaling behavior of the form T χ ′′ (Q, E, T ) = CQf [E/(aQT β Q )] with βQ < 1 is obtained. This scaling does not enter the general framework of quantum phase transition theories, since it is obtained in a high temperature range, where Kondo spin fluctuations depend strongly on temperature.

Magnetic excitations in the spinel compoundLix[Mn1.96Li0.04]Heitmann1, Schmets2, Gaddy3 et al. 2010Phys. Rev. B9040View full textAdd to dashboardCite

“…Thus, if we are to distinguish quantum critical scaling from geometry-induced mimicking of scaling, then we must scrutinize the scaling function itself. In the present work we have found a scaling relation that can be cast into a similar form as the scaling functions found in the literature [12][13][14][15][16]40 IЈ͑q,E,T͒ ϳ Љ͑q,E,T͒…”

“…Aronson et al 13,14 found that UCu 5−x Pd x scales with a =1/ 3 and b = 1 in their original observation of scaling in QCP systems. Further, Schröder et al, 12 Knafo et al, 40 and Montfrooij et al 15 16 reported an exponent of a = 0.2-0.5 ͑and b =1͒ for URu 2−x Re x Si 2 for x = 0.2-0.6, respectively. Note that it is not clear at present, given the range of values reported for the exponent a, whether there is an underlying connection between the exponent a of the scaling relation and the ratio d / z of the effective dimension d and the dynamical exponent z.…”

Magnetic excitations

“…The measured scattering function can be 02003-p. 19 Collection SFN easily related to a microscopic description of the studied system using either matrix elements, spin-spin correlation functions or the dynamical spin susceptibility formalism. Finally polarized Inelastic Neutron Scattering allows not only to unambiguously show the magnetic nature of the measured spectrum but also to gain more insight into detailed characteristics of the magnetic excitation.…”

“…(1.5). Figure 8 shows the scattering function measured in CeRu 2 Si 2 at the wave-vector Q = (0.69, 1, 0) [19]. In this compound, the spin dynamics is basically governed by the Kondo relaxation.…”

Fermion condensate generates a new state of matter by making flat bands

“…The panel A of Fig. 15 reports (T 2/3 χ ′′ ) N extracted from measurements of the inelastic neutron scattering spectrum on the HF metal Ce 0.925 La 0.075 Ru 2 Si 2 [52]. The data (T 2/3 χ ′′ ) N exhibit the scaling behavior over three orders of the variation of both the function and the variable.…”