Intrinsic dielectric properties of magnetodielectric La$_2$CoMnO$_6$

TL;DR

This study investigates the intrinsic dielectric properties of La$_2$CoMnO$_6$, revealing that its colossal dielectric constant is due to extrinsic effects and assessing its suitability for microwave applications.

Contribution

The paper provides a detailed analysis of phonon contributions to dielectric response and clarifies the extrinsic origin of CDC in La$_2$CoMnO$_6$, using infrared spectroscopy.

Findings

CDC in LCMO is of extrinsic origin.

Estimated dielectric constant in microwave region is ~16.

Material shows potential for microwave device applications.

Abstract

Manganites with double perovskite structure are being attractive because of their interesting magnetoelectric and dielectric responses. Particularly, colossal dielectric constant (CDC) behavior has been observed in La$_2$CoMnO$_6$ (LCMO), at radio frequencies and room temperature. In this paper, we employed infrared-reflectivity spectroscopy onto a LCMO ceramic obtained through a modified Pechini's method to determine the phonon contribution to the intrinsic dielectric response of the system and to investigate the CDC origin. The analysis of the main polar modes and of the obtained phonon parameters show that CDC effect of LCMO is of pure extrinsic origin. In addition, we have estimated the dielectric constant and quality factor of the material in microwave region, $e'_s \sim 16$ and $Q_u \times f \sim 124$ THz, which shows that LCMO is appropriate for applications into microwave devices and circuitry.