Electrical half-wave rectification at ferroelectric domain walls

Abstract

Domain walls in ferroelectric semiconductors show promise as multifunctional two-dimensional elements for next-generation nanotechnology. Electric fields, for example, can control the direct-current resistance and reversibly switch between insulating and conductive domain-wall states, enabling elementary electronic devices such as gates and transistors. To facilitate electrical signal processing and transformation at the domain-wall level, however, an expansion into the realm of alternating-current technology is required. Here, we demonstrate diode-like alternating-to-direct current conversion based on neutral ferroelectric domain walls in ErMnO. By combining scanning probe and dielectric spectroscopy, we show that the rectification occurs at the tip-wall contact for frequencies at which the walls are effectively pinned. Using density functional theory, we attribute the responsible transport behaviour at the neutral walls to an accumulation of oxygen defects. The practical frequency regime and magnitude of the direct current output are controlled by the bulk conductivity, establishing electrode-wall junctions as versatile atomic-scale diodes.

Unexpected Giant Microwave Conductivity in a Nominally Silent BiFeO3 Domain Wall

“…On the other hand, while mobile‐carrier conduction and bound‐charge oscillation both contribute to the ac conduction, they are fundamentally different physical processes and should be analyzed separately. It is therefore imperative to obtain a unified picture on these two mechanisms in ferroelectrics DWs, which is crucial for their applications in nanoelectronics …”

An Electronically Driven Improper Ferroelectric: Tungsten Bronzes as Microstructural Analogs for the Hexagonal Manganites

“…The aspiration is that these 2D-'sheet'-materials could therefore be exploited in new forms of agile nano-electronics [4] . Emergent electrical properties of DWs include enhanced or diminished electrical conductivity (both ac and dc) in a wide range of materials including BiFeO3, [5,6] BaTiO3, [7,8] LiNbO3, [9] PZT [10] , KTP [11] , copper-chloride boracites [12] and members of the rare earth manganites (RMnO3, R = Y, Er, Ho) [13][14][15][16][17] . The ambition to exploit DWs with different functionality for nano-electronics, however, stretches beyond simply reconfigurable circuitry which relies on DW conduction to direct current.…”

“…The ambition to exploit DWs with different functionality for nano-electronics, however, stretches beyond simply reconfigurable circuitry which relies on DW conduction to direct current. The functional properties of DWs have also been demonstrated to include more complex behaviour such as rectification [15] and have already been utilized for nanoelectronic devices including diodes [11] , tunnel junctions [8] and non-volatile memories [6] . The electrical behaviour of DWs has been shown to be highly dependent on the nature of the discontinuity in the polarisation at the ferroelectric DW [18] : head-to-head, or tail-to-tail polarisation results in a wall with bound charge.…”

“…The improper ferroelectric [20] rare earth manganites, RMnO3 (R 3+ = Dy, Ho, Er, Tm, Yb, Lu, Y, and Sc), in particular have generated widespread interest as the geometrically-driven improper nature of ferroelectricity results in striking six-domain 'cloverleaf' vertices linked by labyrinthine (meandering) DWs with wide-ranging functionalities [13,[15][16][17] . Specifically the domain microstructure involves interlocking of (structural) antiphase and ferroelectric boundaries [21] to produce the labyrinthine domain structures with six-domain vertices rather than conventional stripe or "tweed" patterns.…”

“…The meandering nature of the domain walls, coupled with the uniaxial polarisation in the system, guarantees that sections of the domain walls will support polarisation discontinuities. In many of the rare-earth manganites, such discontinuities have been associated with enhanced conductivity measured both through conducting atomic force microscopy (cAFM) [13][14][15]44] and localised Hall Effect [16,45] measurements. Initial investigations using cAFM did not reveal enhanced conduction at domain walls in CsNbW2O9, but it is unclear that a percolative pathway from the conducting AFM tip to the electrical earth at the base of the ceramic sample had been established.…”