Interplay between mesoscopic phase separation and bulk magnetism in the layered NaxCoO2

TL;DR

This study investigates how mesoscopic phase separation influences bulk magnetism in layered NaxCoO2 by analyzing specific heat data, revealing the role of quasi-2D antiferromagnetic clusters in magnetic behavior.

Contribution

It provides new insights into the interplay between phase separation and magnetism in NaxCoO2 through detailed specific heat measurements and analysis.

Findings

Mesoscopic phase separation affects magnetic properties.

Quasi-2D antiferromagnetic clusters dominate short-range ordering.

Magnetic behavior varies with sodium content (x).

Abstract

Specific heat of the layered NaxCoO2 (x=0.65, 0.70 and 0.75) oxides has been measured in the temperature range of 3-360 K and magnetic field of 0 and 9 T. The analysis of data, assuming the combined effect of inter-layer superexchange and the phase separation into mesoscopic magnetic domains with localized spins embedded in a matrix with itinerant electronic character, suggests that the dominant contribution to the specific heat in the region of short-range ordering is mediated by quasi-2D antiferromagnetic clusters, perpendicular to the CoO2 layers.