On Electron Transport in ZrB12, ZrB2 and MgB2

TL;DR

This study investigates the electrical resistivity of ZrB12, ZrB2, and MgB2, revealing metallic behavior in ZrB12 with superconductivity at 6.0 K, while ZrB2 shows no superconductivity down to 1.3 K.

Contribution

The paper provides detailed resistivity measurements of ZrB12, ZrB2, and MgB2, highlighting differences in their electronic behavior and superconducting properties.

Findings

ZrB12 behaves as a simple metal with a Bloch-Grüneisen resistivity dependence.

ZrB12 exhibits superconductivity at 6.0 K.

ZrB2 shows no superconductivity down to 1.3 K.

Abstract

We report on measurements of the temperature dependence of resistivity, $\rho(T)$, for single crystal samples of ZrB$_{12}$, ZrB$_{2}$ and polycrystalline samples of MgB$_{2}$. It is shown that cluster compound ZrB$_{12}$ behaves like a simple metal in the normal state, with a typical Bloch -- Gr\"uneisen $\rho(T)$ dependence. However, the resistive Debye temperature, $T_{R}=300 K$, is three times smaller than $T_{D}$ obtained from specific heat data. We observe the $T^{2}$ term in $\rho(T)$ of these borides, which could be interpreted as an indication of strong electron-electron interaction. Although the $\rho (T)$ dependence of ZrB$_{12}$ reveals a sharp superconductive transition at $T_{c}=6.0 K$, no superconductivity was observed for single crystal samples of ZrB$_{2}$ down to $1.3 K$.