Low-magnetic-field control of dielectric constant at room temperature realized in Ba0.5Sr1.5Zn2Fe12O22

TL;DR

This study demonstrates that Ba0.5Sr1.5Zn2Fe12O22 exhibits a significant magnetodielectric effect near room temperature, enabling magnetic control of its dielectric properties through low magnetic fields, facilitated by heat treatment-induced resistivity changes.

Contribution

It reveals a novel low-field magnetic control of dielectric constant at room temperature in Ba0.5Sr1.5Zn2Fe12O22, linked to magnetic field-induced ferroelectricity near its helical spin transition.

Findings

Resistivity increases by over three orders of magnitude after heat treatment.

Magnetodielectric effect of 1.1% observed near room temperature.

Magnetic field-induced ferroelectricity occurs at fields below 0.1 T.

Abstract

We show that room temperature resistivity of Ba0.5Sr1.5Zn2Fe12O22 single crystals increases by more than three orders of magnitude upon being subjected to optimized heat treatments. The increase in the resistivity allows the determination of magnetic field (H)-induced ferroelectric phase boundaries up to 310 K through the measurements of dielectric constant at a frequency of 10 MHz. Between 280 and 310 K, the dielectric constant curve shows a peak centered at zero magnetic field and thereafter decreases monotonically up to 0.1 T, exhibiting a magnetodielectric effect of 1.1%. This effect is ascribed to the realization of magnetic field-induced ferroelectricity at an H value of less than 0.1 T near room temperature. Comparison between electric and magnetic phase diagrams in wide temperature- and field-windows suggests that the magnetic field for inducing ferroelectricity has decreased near its helical spin ordering temperature around 315 K due to the reduction of spin anisotropy in Ba0.5Sr1.5Zn2Fe12O22.