Metal-to-metal transition and heavy-electron state in Nd4Ni3O10−δ

Abstract

The trilayer nickelate ${\mathrm{Nd}}_{4}{\mathrm{Ni}}_{3}{\mathrm{O}}_{10\ensuremath{-}\ensuremath{\delta}}$ was investigated by the measurements of x-ray diffraction, electrical resistivity, magnetic susceptibility, and heat capacity. The crystal structure data suggest a higher Ni valence in the inner perovskitelike layer. At ambient pressure the resistivity shows a jump at 162 K, indicating a metal-to-metal transition (MMT). The MMT is also characterized by a magnetic susceptibility drop, a sharp specific-heat peak, and an isotropic lattice contraction. Below $\ensuremath{\sim}50\phantom{\rule{0.28em}{0ex}}\mathrm{K}$, a resistivity upturn with $logT$ dependence shows up, accompanied with negative thermal expansion. External hydrostatic pressure suppresses the resistivity jump progressively, coincident with the weakening of the $logT$ behavior. The low-temperature electronic specific-heat coefficient is extracted to be $\ensuremath{\sim}150\phantom{\rule{0.28em}{0ex}}\mathrm{mJ}\phantom{\rule{0.28em}{0ex}}{\mathrm{K}}^{\ensuremath{-}2}\phantom{\rule{0.16em}{0ex}}\mathrm{mol}\text{\ensuremath{-}}{\mathrm{f}.\mathrm{u}.}^{\ensuremath{-}1}$, equivalent to $\ensuremath{\sim}50\phantom{\rule{0.28em}{0ex}}\mathrm{mJ}\phantom{\rule{0.28em}{0ex}}{\mathrm{K}}^{\ensuremath{-}2}\phantom{\rule{0.16em}{0ex}}\mathrm{mol}\text{\ensuremath{-}}{\mathrm{Ni}}^{\ensuremath{-}1}$, indicating an unusual heavy-electron correlated state. The novel heavy-electron state as well as the logarithmic temperature dependence of resistivity is explained in terms of the ${\mathrm{Ni}}^{3+}$-centered Kondo effect in the inner layer of the ${({\mathrm{NdNiO}}_{3})}_{3}$ trilayers.