| Summary: | Single crystalline magnetite Fe<sub>3</sub>O<sub>4</sub> was investigated at low temperatures in the charge ordered state by electric measurements and time-resolved diffraction with voltage applied in-situ. Dielectric spectroscopy indicates relaxor ferroelectric characteristics, with polarization switching observably only at sufficiently low temperatures and in a suitably chosen time-window. PUND measurements with a ms time scale indicate a switchable polarization of about 0.6 µC/cm<sup>2</sup>. Significant switching occurs only above a threshold field of about 3 kV/mm, and it occurs with a time delay of about 20 µs. The time-resolved diffraction experiment yields, for sufficiently high voltage pulses, a systematic variation by about 0.1% of the intensity of the (<inline-formula> <math display="inline"> <semantics> <mrow> <mn>2</mn> <mo>,</mo> <mover> <mn>2</mn> <mo>¯</mo> </mover> <mo>,</mo> <mover> <mn>10</mn> <mo>¯</mo> </mover> </mrow> </semantics> </math> </inline-formula>) Bragg reflection, which is attributed to structural switching of domains of the non-centrosymmetric <inline-formula> <math display="inline"> <semantics> <mrow> <mi>C</mi> <mi>c</mi> </mrow> </semantics> </math> </inline-formula> structure to its inversion twins, providing proof of intrinsic ferroelectricity in charge ordered magnetite.
|
|---|
