Magnetic field dependent specific heat and enhanced Wilson ratio in strongly correlated layered cobalt oxide

Abstract

We have investigated the low temperature specific heat properties as a function of magnetic field in the strongly correlated layered cobalt oxide [BiBa${}_{0.66}$K${}_{0.36}$O${}_2$]CoO${}_2$. These measurements reveal two kinds of magnetic field dependent contributions in qualitative agreement with the presence of a previously inferred magnetic Quantum Critical Point (QCP). First, the coefficient of the low temperature T${}^3$ behavior of the specific heat turns out to sizeably decrease near a magnetic field consistent with the critical value reported in a recent paper. In addition, a moderate but significant enhancement of the Sommerfeld coefficient is found in the vicinity of the QCP suggesting a slight increase of the electronic effective mass. This result contrasts with the divergent behavior of the previously reported Pauli susceptibility. Thus, a strongly enhanced Wilson ratio is deduced, suggesting efficient ferromagnetic fluctuations in the Fermi liquid regime which could explain the unusual magnetic field dependent specific heat. As a strong check, the high magnetic field Wilson ratio asymptotically recovers the universal limit of the local Fermi liquid against ferromagnetism.

5 pages, 4 figures

References in corpus (8)

• Fermi-liquid instabilities at magnetic quantum phase transitions
• Scaling behavior in thermoelectric misfit cobalt oxides
• Strain induced pressure effect in pulsed laser deposited thin films of the strongly correlated oxide V2O3
• Interplay between magnetic properties and thermoelectricity in misfit and Na cobaltates
• Magnetoresistance scaling in the layered cobaltate Ca3Co4O9
• From quantum criticality to enhanced thermopower in strongly correlated layered cobalt oxide
• Spin fluctuations, magnetic long-range order and Fermi surface gapping in NaxCoO2
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• ω/T scaling of the optical conductivity in strongly correlated layered cobalt oxide
• Tomonaga-Luttinger liquid and quantum criticality in spin-1/2 antiferromagnetic Heisenberg chain C14H18CuN4O10 via Wilson ratio
• Signatures of a Majorana-Fermi surface in the Kitaev magnet Ag${}_3$LiIr${}_2$O${}_6$