Magnetotransport properties governed by antiferromagnetic fluctuations in the heavy-fermion superconductorCeIrIn5

Abstract

In quasi-two-dimensional Ce͑Ir, Rh͒In 5 system, it has been suggested that the phase diagram contains two distinct domes with different heavy-fermion superconducting states. Here, we report the systematic pressure dependence of the electron transport properties in the normal state of CeRh 0.2 Ir 0.8 In 5 and CeIrIn 5 , which locates in first and second superconducting domes, respectively. We observed non-Fermi liquid behavior at low temperatures in both compounds, including nonquadratic T dependence of the resistivity, large enhancement of the Hall coefficient, and the violation of the Kohler rule in the magnetoresistance. We show that the cotangent of the Hall angle cot ⌰ H varies as T 2 , and the magnetoresistance is quite scaled well by the Hall angle as ⌬ xx / xx ϰ tan 2 ⌰ H . The observed transport anomalies are common features of CeMIn 5 ͑M = Co, Rh, and Ir͒ and high-T c cuprates, which suggest that the anomalous transport properties observed in CeIrIn 5 are mainly governed by the antiferromagnetic spin fluctuations not by the Ce-valence fluctuations, which have been proposed to be the possible origin for the second superconducting dome.

Valence Fluctuations Revealed by Magnetic Field and Pressure Scans: Comparison with Experiments in YbXCu4(X=In, Ag, Cd) and CeYIn5(Y=Ir, Rh)

“…89) It has been also reported that the magnetotransport measurements under pressures can be understood from the effects of AF spin fluctuations. 90) However, the clear difference between CeIrIn 5 and CeCoIn 5 emerging in the T-h phase diagram mentioned in §4.2 cannot be explained only from the sole viewpoint of the closeness to the AF QCP. In addition to the AF QCP, the influence of the QCP of the FOVT is indispensable for the comprehensive understanding.…”

“…It has been reported that magnetotransport measurement under pressure can be explained by AF spin fluctuations. 90) We think that, in addition to the influence of the AF QCP, the viewpoint of the closeness to the QCP of the FOVT is necessary for the comprehensive understanding of CeIrIn 5 . To examine our theoretical proposal, it is highly desired to experimentally determine whether the change in Ce valence occurs at the FOVT T v ðhÞ in the h-T phase diagram.…”

Progress in Heavy-Fermion Superconductivity: Ce115 and Related Materials

“…6, is reminiscent of that in CeRhIn 5 , but in CeIrIn 5 there is no long range magnetic order nor any other identified broken symmetry competing with superconductivity. Nevertheless, at atmospheric pressure, the nuclear spin relaxation rate 1=T 1 87,94) as well as longitudinal and transverse resistivities 95) have non-Fermi-liquid temperature dependences above the resistive transition that are similar to those of CeCoIn 5 and suggest the proximity of CeIrIn 5 to an antiferromagnetic quantum critical point. This view is supported by an analysis of NMR experiments that gives temperature dependences of the dynamical susceptibility Im ðQ; !…”

“…96) On the other hand, at pressures above 2 GPa 1=T 1 remains T 3 below T c , the Sommerfeld coefficient, though reduced, is still $250 mJ/(mol K 2 ), and the longitudinal and Hall resistivities are non-Fermi-liquid like. 95,96) A possible rationalization of these apparent inconsistencies is that, as pressure moves CeIrIn 5 away from a magnetic quantum critical regime, critical valence fluctuations begin to control normal and superconducting state properties. A conclusive test of this scenario, however, is lacking.…”

Hall Effect in CeCu2Si2under Pressure

“…9,10) However, the systematic transport measurement including Hall effect suggested the existence of the AFM spin fluctuation in CeIrIn 5 under pressure. 11) In this 115-system, weak anomalous Hall * E-mail address: araki@science.okayama-u.ac.jp effect, 12) which usually governs the temperature dependence of the Hall coefficient in heavy fermion systems, 13,14) enable the detail discussion from the Hall effect measurement.…”