Thermoelectric behavior of Ruddlesden-Popper series iridates

TL;DR

This study investigates the thermoelectric properties of Ruddlesden-Popper iridates, revealing complex behaviors linked to magnetic and electronic interactions across different compounds with varying bandwidths.

Contribution

It provides a comprehensive analysis of thermoelectric transport in Srn+1IrnO3n+1 iridates, highlighting the role of charge carrier dynamics, phonons, and spin fluctuations.

Findings

Seebeck behavior driven by thermal diffusion in Sr2IrO4

Additional drag mechanisms influence Seebeck in Sr3Ir2O7 and SrIrO3

Strong coupling between charge carriers, phonons, and spin fluctuations

Abstract

The goal of this work is studying the evolution of thermoelectric transport across the members of the Ruddlesden-Popper series iridates Srn+1IrnO3n+1, where a metal-insulator transition driven by bandwidth change occurs, from the strongly insulating Sr2IrO4 to the metallic non Fermi liquid behavior of SrIrO3. Sr2IrO4 (n=1), Sr3Ir2O7 (n=2) and SrIrO3 (n=inf.) polycrystals are synthesized at high pressure and characterized by structural, magnetic, electric and thermoelectric transport analyses. We find a complex thermoelectric phenomenology in the three compounds. Thermal diffusion of charge carriers accounts for the Seebeck behavior of Sr2IrO4, whereas additional drag mechanisms come into play in determining the Seebeck temperature dependence of Sr3Ir2O7 and SrIrO3. These findings reveal close relationship between magnetic, electronic and thermoelectric properties, strong coupling of charge carriers with phonons and spin fluctuations as well as relevance of multiband description in these compounds.