We have synthesized and characterized the physical properties of a layered,
mixed valent oxypnictide
La3Cu4P4O2 via magnetization,
electrical resistivity, and specific heat measurements. Although
La3Cu4P4O2 does not exhibit superconductivity down to T
= 0.5 K, it demonstrates an intriguing resistivity minimum observed at
Tmin = 13.7 K. Disappearance of the resistivity minimum under an
applied magnetic field of
μ0H = 9 T together with the negative
magnetoresistance at low and positive at high temperatures are observed, which
are typical for both Kondo-like spin-dependent scattering and 3D weak
localization. We argue that the Kondo scattering is a more plausible
explanation due to the low-temperature deviation from a Curie-Weiss law
observed in the magnetic susceptibility, consistent with the presence of
magnetic interactions between paramagnetic
Cu2+ ions and Kondo
screening of these
Cu2+ moments. We supplemented the experimental
characterization with a detailed description of chemical bonding, employing
density functional theory (DFT) calculations and crystal orbital Hamilton
population (COHP) analysis for
La3Cu4P4O2 and
isostructural
La3Ni4P4O2, which is a superconductor with
Tc=2.2 K. Based on the calculations performed, we present the
difference between
La3Cu4P4O2 and
La3Ni4P4O2 in the character of electronic states at the
Fermi level. This discrepancy impacts structural stability and may cause a lack
of superconductivity in
La3Cu4P4O2 down to T = 0.5 K.