Stahlbetonbrücken

Frustration in the coupled rattler systemKOs2O6

“…The dynamics of Rb and Cs ions is very different: the local behavior is quite different due to the larger ionic radii which gives a different energy scale, and this distinction in turn negates the inter-site interaction, leaving a simple quasiharmonic local mode. This result of our first principle calculations fits well with the observed specific heat and conductivity [9,15].…”

“…Within this approximation Rb (Cs) dynamics is described by 3D oscillator with a frequency of 44 K (61 K). Recent analysis of specific heat data by Brühwiler et al [9] led to a frequency of 60 K for RbOs 2 O 6 , which we find a reasonable agreement given the approximations. Localized modes were previously observed in specific heat of RbOs 2 O 6 and CsOs 2 O 6 by Hiroi et al [15] The harmonic oscillator root mean square displacement is…”

“…Recently an intriguing λ-shaped peak in the specific heat was observed in good quality KOs 2 O 6 single-crystals indicative of a phase transition at T p = 7 K [10], within the superconducting state. This observation was recently confirmed [9]. Notably, the peak position and shape do not change even when the superconductivity is suppressed below 7 K by the external field.…”

“…Unexpectedly large variation of the superconducting T c throughout the group (from 3.3 K in CsOs 2 O 6 to 9.7 K in KOs 2 O 6 ) [1, 2, 3] together with reports of anomalous nuclear spin relaxation [4] and indications of anisotropic order parameter [5] in KOs 2 O 6 pointed to a possibility of unconventional pairing and fueled the early experimental interest. While the issue of superconductivity remains controversial in the light of recent pressure experiments [1], unusual transport and thermodynamic properties were found in the normal state of KOs 2 O 6 in sharp contrast to the standard metallic behavior of RbOs 2 O 6 and CsOs 2 O 6 [6, 7, 8].Uniquely to KOs 2 O 6 within this class, the normal-state conductivity exhibits a non-Fermi-liquid behavior characterized by a concave temperature dependency down to low temperatures [9,10]. The low temperature linear specific heat coefficient is estimated to be substantially larger than in RbOs 2 O 6 and CsOs 2 O 6 [10].…”

“…Uniquely to KOs 2 O 6 within this class, the normal-state conductivity exhibits a non-Fermi-liquid behavior characterized by a concave temperature dependency down to low temperatures [9,10]. The low temperature linear specific heat coefficient is estimated to be substantially larger than in RbOs 2 O 6 and CsOs 2 O 6 [10].…”