Non-Fermi Liquid Behavior in the Magnetotransport of CeMIn₅ (M: Co and Rh): Striking Similarity between Quasi Two-Dimensional Heavy Fermion and High-T_c Cuprates

Abstract

We present a systematic study of the dc-resistivity, Hall effect, and magnetoresistance in the normal state of quasi two-dimensional (2D) heavy fermion superconductors CeMIn 5 (M: Rh and Co) under pressure. Here the electronic system evolves with pressure from an antiferromagnetic (AF) metal, through a highly unconventional non-Fermi liquid, and finally into a Fermi-liquid state. The novelty of these materials is best highlighted when compared with LaMIn 5 , a system with similar electronic structures, which shows a nearly temperature independent Hall coefficient and a magnetoresisitance which is well described by the classical Kohler's rule. In sharp contrast, in CeMIn 5 , the amplitude of the Hall coefficient increases dramatically with decreasing temperature, reaching at low temperatures a value significantly larger than 1=ne, where n is the carrier number. Furthermore, the magnetoresistance is characterized by T-and H-dependence which clearly violate Kohler's rule. We found that the cotangent of the Hall angle cot  H varies as T 2 , and the magnetoresistance is well scaled by the Hall angle as Á xx = xx / tan 2  H . These non-Fermi liquid properties in the electron transport are remarkably pronounced when the AF fluctuations are enhanced in the vicinity of the quantum critical point. We lay particular emphasis on the striking resemblance of these anomalous magnetotransport with those of the high-T c cuprates. We argue that features commonly observed in quasi 2D heavy fermion and cuprates very likely capture universal features of strongly correlated electron systems in the presence of strong AF fluctuations, holding the promise of bridging our understanding of heavy fermion systems and high-T c cuprates.

Impurity Effects in Sign-Reversing Fully Gapped Superconductors: Analysis of FeAs Superconductors

“…The resonance peak observed by inelastic neutron measurement below T c supports the sign-reversing superconducting gap mediated by AF fluctuations [27,28]. Anomalous transport phenomena (such as Hall coefficient and Nernst signal) in the normal state in FeAs, which are similar to those observed in high-T c cuprates and CeM In 5 (M =Co, Rh, Ir) [29], also indicate the existence of strong AF fluctuations [10,12,30,31]. On the other hand, impurity effect on T c due to Co, Ni, or Zn substitution for Fe sites is very small or absent [11,12,[32][33][34], which is decisive for determining the pairing symmetry.…”

Heavy fermion superconductor CeCu2Si2under high pressure: Multiprobing the valence crossover

“…47 Deviations from this standard behavior are also observed, for example, in CeRhIn 5 , where magnetoresistance violates Kohler's rule in the p region exhibiting prominent non-Fermi liquid properties, but satisfies a modified scaling relation. 48 From our partial analysis (not shown) on CeCu 2 Si 2 , no significant deviation from Kohler's rule throughout the investigated p range can be deduced. However, this preliminary statement still requires substantiation from supplementary data, especially at high p where ρ(T < 4 K) hardly varies, meaning that data points above 4 K should be included in order to perform the test on a broad parameter range.…”

“…Interestingly, an enhancement of ρ xy at low T is also reported in CeRhIn 5 close to the critical pressure p c ∼ p V and discussed in the light of the backflow effect in strongly correlated materials. 48 Further calculations within the critical VF scenario are currently carried out and may connect on a microscopic basis the observed increase of ρ xy (p) in vicinity of p V with the 4f electron delocalization and the proximity to the CEP in CeCu 2 Si 2 . agree with previous reports, 6,46,53 except that at p = 0 we obtain a slightly smaller signal from the A phase (not shown) compared to Ref.…”

A theoretical evaluation of magnetoresitance (magneto transport property) of some heavy-fermion superconductors

“…It has been observed that the magnetoresistance in CeRhIn5 with similar electronic structure but weak electronic correlation obey the Kohler's rule 22 . It has also been observed that magnetoresistance strongly violates the Kohler's rule in the case of CeCoIn5 and CeRhIn5 33 .…”