Relaxor ferroelectricity and the freezing of short-range polar order in magnetite

TL;DR

This study reveals relaxor-like polar order in magnetite, showing that the freezing of short-range polar order prevents long-range ferroelectricity and leads to a glasslike state at low temperatures.

Contribution

It provides experimental evidence for relaxor ferroelectric behavior and short-range charge order in magnetite, challenging previous assumptions of long-range ferroelectricity below the Verwey transition.

Findings

Evidence of relaxor-like polar order in magnetite

Freezing of polar degrees leads to a glasslike state

Charge order is likely short-range and tunneling-dominated at low temperatures

Abstract

A thorough investigation of single crystalline magnetite using broadband dielectric spectroscopy and other methods provides evidence for relaxor-like polar order in Fe3O4. We find long-range ferroelectric order to be im-peded by the continuous freezing of polar degrees of freedom and the formation of a tunneling-dominated glasslike state at low temperatures. This also explains the lack of clear evidence for a non-centrosymmetric crystal structure below the Verwey transition. Within the framework of recent models assuming an intimate relation of charge and polar order, the charge order, too, can be speculated to be of short-range type only and to be dominated by tunneling at low temperatures.