Metal-to-metal transition and heavy-electron state in Nd${}_4$Ni${}_3$O${}_{10-\hat{I}´}$

Abstract

The trilayer nickelate Nd${}_4$Ni${}_3$O${}_{10-\hat{I}´}$ ($\hat{I}´\approx$ 0.15) 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 perovskite-like 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 $\sim$ 50 K, a resistivity upturn with a log$T$ dependence shows up, accompanying with a negative thermal expansion. External hydrostatic pressure suppresses the resistivity jump progressively, coincident with the diminution of the log$T$ behavior. The low-temperature electronic specific-heat coefficient is extracted to be $\sim$ 150 mJ K${}^{-2}$ mol-fu${}^{-1}$, equivalent to $\sim$ 50 mJ K${}^{-2}$ mol-Ni${}^{-1}$, 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 Ni${}^{3+}$ centered Kondo effect in the inner layer of the (NdNiO${}_3$)${}_3$ trilayers.

10 pages, 6 figures, and 1 table; The high-pressure study was supplemented