YbRh2Si2: Pronounced Non-Fermi-Liquid Effects above a Low-Lying Magnetic Phase Transition

Abstract

We report the first observation of non-Fermi-liquid (NFL) effects in a clean Yb compound at ambient pressure and zero magnetic field. The electrical resistivity and the specific-heat coefficient of high-quality single crystals of YbRh(2)Si(2) present a linear and a logarithmic temperature dependence, respectively, in more than a decade in temperature. We ascribe this NFL behavior to the presence of (presumably) quasi-2D antiferromagnetic spin fluctuations related to a very weak magnetic phase transition at T(N) approximately 65 mK. Application of hydrostatic pressure induces anomalies in the electrical resistivity, indicating the stabilization of magnetic order.

Disorder, inhomogeneity and spin dynamics in f-electron non-Fermi liquid systems

“…A number of bulk measurements [30] indicate that YbRh 2 Si 2 exhibits antiferromagnetism with a very low Néel temperature T N ≈ 70 mK, with a fieldinduced QCP at the orientation-dependent critical field H c that suppresses T N to zero. Resistivity and specific heat measurements at low temperatures show ∆ρ ∝ T and C el /T ∝ − ln T over a temperature range of more than a decade.…”

“…At ambient pressure these include CeCu 5.9 Au 0.1 [23][24][25], Ce(Ru 1−x Rh x ) 2 Si 2 , x ≈ 0.5 [26,27], CeNi 2 Ge 2 [28,29], and YbRh 2 Si 2 [30]. Thus one can compare spin dynamics in 'disordered' and 'ordered' materials.…”

Band-structure and anomalous contributions to the Hall effect of YbRh2Si2

“…Single crystals of YbRh 2 Si 2 and LuRh 2 Si 2 were synthesized with an In flux-growth technique as described earlier [1]. All samples were polished to thin plates and prescreened via rðT; BÞ to ensure In free samples.…”

“…YbRh 2 Si 2 is a stoichiometric heavy fermion (HF) compound showing non-Fermi-liquid (NFL) properties in a wide temperature range above the antiferromagnetic transition at T N ¼ 70 mK [1]. T N is found to be continuously suppressed with small magnetic fields to T ¼ 0 accessing the quantum critical point (QCP) [2].…”

Anomalies of transport properties in antiferromagnetic compound

“…Typically, a T-linear resistivity can be observed near the quantum critical point, as it takes place, e.g.., in YbRh 2 Si 2 [14]. One of possible reasons of such a behavior in some region is scattering by antiferromagnetic fluctuations, especially in the case of nested Fermi surface [15].…”