Structural correlation to enhanced magnetodielectric properties of Pr-doped polycrystalline Gd$_{0.55}$Pr$_{0.45}$MnO$_3$ at low temperatures

TL;DR

This study demonstrates that Pr doping in GdMnO3 enhances its magnetodielectric properties at low temperatures, with structural stability and reduced octahedral distortion contributing to improved dielectric and magnetic behaviors.

Contribution

It provides detailed structural, dielectric, and magnetic analysis of Pr-doped GdMnO3, revealing the correlation between structure and enhanced magnetodielectric effects at low temperatures.

Findings

Enhanced dielectric permittivity under magnetic field

Orthorhombic Pnma symmetry confirmed from 300 K to 50 K

Negative magnetization due to spin canting observed at low temperatures

Abstract

The effect of improved dielectric properties in the presence of an applied magnetic field is discussed in Pr doped polycrystalline Gd$_{0.55}$Pr$_{0.45}$MnO$_3$ complemented by the structural properties down to 50 K and magnetic properties. Enhanced dielectric permittivity and low dielectric loss represent the strongly field-dependent dielectric behaviour of the sample. The structural characterizations using synchrotron angle dispersive X-ray diffraction confirm the orthorhombic symmetry of the polycrystalline sample with the Pnma space group from 300 K to 50 K. There is no structural transition at lower temperatures up to 50 K; however the Mn O octahedral distortion is reduced. The investigation of dielectric properties for frequencies range 500 Hz to 1 MHz was conducted in the temperature range 8 K to 300 K with and without a magnetic field of 7 Tesla, which shows the high dielectric constant in the 500 Hz frequency region. This confirms the relaxation phenomena in polycrystalline Gd$_{0.55}$Pr$_{0.45}$MnO$_3$. ac conductivity data shows the increasing trend for frequencies along with the activation energy which increases from low frequencies to higher frequencies. Temperature-dependent dc magnetization study shows the negative magnetization in polycrystalline Gd$_{0.55}$Pr$_{0.45}$MnO$_3$ at low temperature at 100 Oe applied field, due to spin canting of Mn-Mn magnetic lattice. High coercivity due to competition in between spin ordering of Mn and Gd,Pr magnetic lattice at 5 K are also observed in the field-dependent magnetization study.