Possible Griffiths effects in the layered Nax CoO2
Alexander Fehera , Anna Zorkovskáa, Martin Orendáča, Alžbeta Orendáčováa, Erik Čižmára, Slavomir
Gabánia , Ivica Bradarićb, and Ilija Savićc
a
Centre of Low Temperature Physics, P. J. Šafárik University & Slovak Academy of Science, Park Angelinum 9, 04154 Košice, Slovakia
b
The ”Vinča” Institute of Nuclear Sciences, P.O. Box 552, 11001 Belgrade, Serbia and Montenegro
c
Faculty of Physics, University of Belgrade, Studentski trg 12-14, 11000 Belgrade, Serbia and Montenegro
Specific heat of the layered cobalt oxide system Nax CoO2 (x=0.65, 0.70, 0.75), that represents the
outgoing material for the hydrated superconducting cobaltates, has been measured by dual slope method
on 3 He -4 He refrigerator TLE-2000 Oxford Instruments, in the low temperature region of 0.5 - 3 K. The
powdered samples, prepared by the rapid heat-up method, were confirmed to be single phase hexagonal
γ-Nax CoO2 .
The specific heat data analysis, taking into consideration our previous susceptibility measurements, suggests possible non-Fermi liquid behaviour of the correlated electronic states in the system. The divergency
of thermodynamic quantities can be described by a common power law within a Griffiths phase scenario
rather than in the spin fluctuation one. The parameter λ in the power exponent bears relation to the
electron doping level.
Sorting category: Ce Magnetism and properties of solids
Keywords: strongly correlated systems, Griffiths phase, non-Fermi liquid
LT1575