Conductivity sum rule , implication for in - plane dynamics and c - axis response
نویسندگان
چکیده
Recently observed c-axis optical sum rule violations indicate non-Fermi liquid in-plane behavior. For coherent c-axis coupling, the observed flat, nearly frequency independent c-axis conductivity σ 1 (ω) implies a large in-plane scattering rate Γ around (0, π) and therefore any pseudogap that might form at low frequency in the normal state will be smeared. On the other hand incoherent c-axis coupling places no restriction on the value of Γ and gives a more consistent picture of the observed sum rule violation which, we find in some cases, can be less than half.
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