Evidence of variable range hopping in the Zintl phase EuIn2P2

TL;DR

This study thoroughly characterizes EuIn2P2, revealing variable-range hopping as the dominant electrical conduction mechanism above 40K, alongside its magnetic and thermal properties, indicating complex interactions in this Zintl phase.

Contribution

It provides the first detailed analysis of EuIn2P2's magnetic, electrical, spectral, and thermal properties, highlighting variable-range hopping as a key conduction process.

Findings

Electrical resistivity follows variable-range hopping model.

Negative magnetoresistance shows quadratic dependence on magnetic field.

Magnetic ordering occurs at 24K with Eu2+ moments.

Abstract

We report a comprehensive characterization of the magnetic, electrical transport, spectral, and thermal properties of single-crystalline Zintl-type material EuIn2P2. The compound crystallizes with a hexagonal unit cell (space group P63/mmc) and orders magnetically at TC=24K with the Eu magnetic moments aligned ferromagnetically within the ab plane but tilted alternately along the c-axis direction. The effective and saturation magnetic moments agree with the theoretical values expected for the Eu2+ ion. For a range of several tens of kelvins above 40K, the electrical transport of EuIn2P2 is dominated by short-range magnetic interactions. The temperature dependence of the electrical resistivity has been modelled in terms of variable-range hopping. Another indication of the latter scenario seems to be the observation for EuIn2P2 of a quadratic dependence of the negative magnetoresistance on the magnetic field strength and the scaled magnetization. The temperature dependence of Raman band position and FWHM, as well as phonon lifetime, confirms the presence of the distinctive regions observed in transport and magnetic studies.