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A diode for ferroelectric domain-wall motion.

Whyte JR, Gregg JM - Nat Commun (2015)

Bottom Line: Revolutionary technologies have resulted, like racetrack memory and domain-wall logic.Until recently, equivalent research in analogous ferroic materials did not seem important.Domain walls can move readily in the direction in which thickness increases gradually, but are prevented from moving in the other direction by the sudden thickness increase at the sawtooth edge.

View Article: PubMed Central - PubMed

Affiliation: Centre for Nanostructured Media, School of Maths and Physics, Queen's University Belfast, University Road, Belfast BT7 1NN, UK.

ABSTRACT
For over a decade, controlling domain-wall injection, motion and annihilation along nanowires has been the preserve of the nanomagnetics research community. Revolutionary technologies have resulted, like racetrack memory and domain-wall logic. Until recently, equivalent research in analogous ferroic materials did not seem important. However, with the discovery of sheet conduction, the control of domain walls in ferroelectrics has become vital for the future of what has been termed 'domain-wall electronics'. Here we report the creation of a ferroelectric domain-wall diode, which allows a single direction of motion for all domain walls, irrespective of their polarity, under a series of alternating electric field pulses. The diode's sawtooth morphology is central to its function. Domain walls can move readily in the direction in which thickness increases gradually, but are prevented from moving in the other direction by the sudden thickness increase at the sawtooth edge.

No MeSH data available.


Domain pinning at ledge and increased mobility on moving down the ramp.(a,b) PFM scans on the left showing the topography (top), amplitude (middle) and phase (bottom) with the average phase and topography signals displayed in a graph on the right, highlighting the domain-wall position in relation to the ledge of the ramp. (a) −25 V moved the domain wall off the ledge from the position shown in Fig. 3e. (b) +32 V moved the domain wall back to the ledge where it remained pinned. (c) PFM information of the morphology (top), amplitude (left) and phase (right), of two domain walls where one is situated in the ramp and the other in the injection pad. After the application of a +50 V pulse, the domain wall in the ramp moves further than that in the injection pad, highlighting the domain-wall preference to move into regions of lower thickness (and hence lower potential). Scale bar is 2 μm in length.
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f4: Domain pinning at ledge and increased mobility on moving down the ramp.(a,b) PFM scans on the left showing the topography (top), amplitude (middle) and phase (bottom) with the average phase and topography signals displayed in a graph on the right, highlighting the domain-wall position in relation to the ledge of the ramp. (a) −25 V moved the domain wall off the ledge from the position shown in Fig. 3e. (b) +32 V moved the domain wall back to the ledge where it remained pinned. (c) PFM information of the morphology (top), amplitude (left) and phase (right), of two domain walls where one is situated in the ramp and the other in the injection pad. After the application of a +50 V pulse, the domain wall in the ramp moves further than that in the injection pad, highlighting the domain-wall preference to move into regions of lower thickness (and hence lower potential). Scale bar is 2 μm in length.

Mentions: Figure 4a,b highlights the effectiveness of the steep ramp ledge in preventing domain-wall motion: a domain-wall which was initially driven up the shallow ramp slope and just over the edge of the ramp using a negative applied voltage (−55 V as above) was moved further from right to left using a −25 V pulse. By then reversing the pulse, to the +32 V value used to generate the switching seen in Fig. 3f, the domain wall is seen to nestle into the steep edge of the ramp, but not progress further. The potential barrier associated with the sharp edge of the ramp is obviously key to the realization of the ferroelectric domain-wall diode demonstrated. In Fig. 4c a domain wall has been moved up the shallow incline of the ramp, but has not been moved over the ledge (it stopped short of the ledge during the initial switching pulse). On reversal of the field, this domain wall moves readily down the ramp, as it is not pinned. Indeed, its motion is enhanced relative to another wall travelling in a flat part of the diode structure: its wall area is decreasing as it moves and it is thus travelling down the potential gradient.


A diode for ferroelectric domain-wall motion.

Whyte JR, Gregg JM - Nat Commun (2015)

Domain pinning at ledge and increased mobility on moving down the ramp.(a,b) PFM scans on the left showing the topography (top), amplitude (middle) and phase (bottom) with the average phase and topography signals displayed in a graph on the right, highlighting the domain-wall position in relation to the ledge of the ramp. (a) −25 V moved the domain wall off the ledge from the position shown in Fig. 3e. (b) +32 V moved the domain wall back to the ledge where it remained pinned. (c) PFM information of the morphology (top), amplitude (left) and phase (right), of two domain walls where one is situated in the ramp and the other in the injection pad. After the application of a +50 V pulse, the domain wall in the ramp moves further than that in the injection pad, highlighting the domain-wall preference to move into regions of lower thickness (and hence lower potential). Scale bar is 2 μm in length.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4490414&req=5

f4: Domain pinning at ledge and increased mobility on moving down the ramp.(a,b) PFM scans on the left showing the topography (top), amplitude (middle) and phase (bottom) with the average phase and topography signals displayed in a graph on the right, highlighting the domain-wall position in relation to the ledge of the ramp. (a) −25 V moved the domain wall off the ledge from the position shown in Fig. 3e. (b) +32 V moved the domain wall back to the ledge where it remained pinned. (c) PFM information of the morphology (top), amplitude (left) and phase (right), of two domain walls where one is situated in the ramp and the other in the injection pad. After the application of a +50 V pulse, the domain wall in the ramp moves further than that in the injection pad, highlighting the domain-wall preference to move into regions of lower thickness (and hence lower potential). Scale bar is 2 μm in length.
Mentions: Figure 4a,b highlights the effectiveness of the steep ramp ledge in preventing domain-wall motion: a domain-wall which was initially driven up the shallow ramp slope and just over the edge of the ramp using a negative applied voltage (−55 V as above) was moved further from right to left using a −25 V pulse. By then reversing the pulse, to the +32 V value used to generate the switching seen in Fig. 3f, the domain wall is seen to nestle into the steep edge of the ramp, but not progress further. The potential barrier associated with the sharp edge of the ramp is obviously key to the realization of the ferroelectric domain-wall diode demonstrated. In Fig. 4c a domain wall has been moved up the shallow incline of the ramp, but has not been moved over the ledge (it stopped short of the ledge during the initial switching pulse). On reversal of the field, this domain wall moves readily down the ramp, as it is not pinned. Indeed, its motion is enhanced relative to another wall travelling in a flat part of the diode structure: its wall area is decreasing as it moves and it is thus travelling down the potential gradient.

Bottom Line: Revolutionary technologies have resulted, like racetrack memory and domain-wall logic.Until recently, equivalent research in analogous ferroic materials did not seem important.Domain walls can move readily in the direction in which thickness increases gradually, but are prevented from moving in the other direction by the sudden thickness increase at the sawtooth edge.

View Article: PubMed Central - PubMed

Affiliation: Centre for Nanostructured Media, School of Maths and Physics, Queen's University Belfast, University Road, Belfast BT7 1NN, UK.

ABSTRACT
For over a decade, controlling domain-wall injection, motion and annihilation along nanowires has been the preserve of the nanomagnetics research community. Revolutionary technologies have resulted, like racetrack memory and domain-wall logic. Until recently, equivalent research in analogous ferroic materials did not seem important. However, with the discovery of sheet conduction, the control of domain walls in ferroelectrics has become vital for the future of what has been termed 'domain-wall electronics'. Here we report the creation of a ferroelectric domain-wall diode, which allows a single direction of motion for all domain walls, irrespective of their polarity, under a series of alternating electric field pulses. The diode's sawtooth morphology is central to its function. Domain walls can move readily in the direction in which thickness increases gradually, but are prevented from moving in the other direction by the sudden thickness increase at the sawtooth edge.

No MeSH data available.