NaxCoO2: Enhanced low-energy excitations of electrons on a 2D triangular lattice
arXiv:cond-mat/0601580 · doi:10.1016/j.physb.2006.01.422
Abstract
To elucidate the low-energy excitation spectrum of correlated electrons on a 2D triangular lattice, we have studied the electrical resistance and specific heat down to 0.5 K and in magnetic fields up to 14 T, in NaxCoO2 samples with a Na content ranging from x \approx 0.5 to 0.82. Two distinct regimes are observed: for x from about 0.6 to x \approx 0.75 the specific heat is strongly enhanced, with a pronounced upturn of C/T below about 10 K, reaching 47 mJ/(mol K^2). This enhancement is suppressed in a magnetic field indicative of strong low-energy spin fluctuations. At higher Na content the fluctuations are reduced and mu-SR data confirm the SDW ground state below 22 K and the much reduced heat capacity is field independent.
Accepted in Physica B
Cited by in corpus (4)
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- Local moment, itinerancy and deviation from Fermi liquid behavior in NaCoO for
- Magnetic fluctuations and specific heat in NaxCoO2 near a Lifshitz topological transition
- Spin fluctuations, magnetic long-range order and Fermi surface gapping in NaxCoO2