Absence of dipolar ordering in Co doped CuO

TL;DR

This study investigates Co-doped CuO, revealing structural changes, altered magnetic transitions, giant dielectric constants, and the absence of ferroelectricity, highlighting the impact of Co doping on CuO's multiferroic properties.

Contribution

The paper demonstrates that Co doping in CuO suppresses ferroelectricity despite giant dielectric constants, providing insights into the valence states and magnetic behavior.

Findings

Structural distortion increases with Co doping.

Giant dielectric constant observed without ferroelectricity.

Suppression of ferroelectric order linked to valence states.

Abstract

Polycrystalline CuO samples with Co doping were prepared by solid state method with flowing oxygen condition and examined their structural and multiferroic properties. Structural studies have confirmed single phase monoclinic crystal structure of all samples, however, in Co doped samples a decrease in volume with an increase in monoclinic distortion is found. For pristine sample, temperature dependent magnetization has confirmed two antiferromagnetic (AFM) transitions at 213 K and 230 K and frequency independent dielectric peaks at these AFM transitions suggesting the ferroelectric nature. Magnetization of the Co doped samples has showed a marginal increase in ordering temperature of the high-temperature AFM transition and decrease in low temperature AFM ordering temperature. Further, doped samples have shown giant dielectric constant with no signature of ferroelectricity. The x-ray photoelectric spectroscopy study has revealed multiple valance states for both Co and Cu in the doped samples that simultaneously explain the giant dielectric constant and suppression of ferroelectric order.