Real-Time 3D Imaging of Nanoscale Ferroelectric Domain
Wall Dynamics in Lithium Niobate Single Crystals under Electric Stimuli:
Implications for Domain-Wall-Based Nanoelectronic Devices
Benjamin Kirbus
Christian Godau
Lukas Wehmeier
Henrik Beccard
Elke Beyreuther
Alexander Haußmann
Lukas M. Eng
10.1021/acsanm.9b01240.s001
https://acs.figshare.com/articles/journal_contribution/Real-Time_3D_Imaging_of_Nanoscale_Ferroelectric_Domain_Wall_Dynamics_in_Lithium_Niobate_Single_Crystals_under_Electric_Stimuli_Implications_for_Domain-Wall-Based_Nanoelectronic_Devices/9807857
Challenges
in the fields of renewable energy harvesting, data storage,
and nanoelectronics have resparked interest in ferroelectric domain
walls (DWs) as tunable, nanoscale elements. However, the study of
such structures has mostly relied on 2-dimensional, rather slow imaging
techniques such as scanning probe microscopy. Therefore, Cherenkov
second harmonic generation (CSHG) microscopy has been established
as a technique suitable for the nondestructive imaging of ferroelectric
DWs and their 3-dimensional (3D) evolution. Here, we report on the
real-time and <i>in situ</i> 3D DW kinetics when inspecting
electrical-field-biased 200 μm thick lithium niobate (LNO) single
crystals. A linear electric field increase up to +4.0 kV/mm (antiparallel
to the direction of spontaneous polarization <i>P</i><sub>S</sub>) resulted in the collapse of laser-poled hexagonal domains
into cone-like structures. The average inclination was measured to
rise up to 2.5°. Head-to-head (h2h) domain walls dominated. Simultaneously,
the domain wall current (DWC) was recorded <i>in situ</i>. It increased by 4 orders of magnitude to 1 μA. The DW mobility
increased dramatically as a function of depth. Moreover, a significant
asymmetry was found, as DW mobility was much higher along crystallographic
(<i>Y</i>+) directions. Subsequently, the electric field
was reversed and swept to −3.6 kV/mm. While the hexagonal domain
shapes were restored for moderate electric fields, the domains separated
into many nucleating spike domains when exceeding a critical threshold
of −3.5 kV/mm. DWC increased dramatically through this process,
reaching magnitudes of up to 1 mA. The understanding of DW dynamics
upon electric stimulation was used to realize a two-port DW-based
nanoswitch. Alternating positive and negative electric fields were
applied to a neutral hexagonal domain contacted purely via solid electrodes.
The field strengths were kept well below the critical threshold of
spike domain formation. The electrical conductivity of such a device
could be tuned over 4 orders of magnitude, i.e., deliberately switched
on and off. Our findings support the development of future DW-based
nanoelectronic devices.
2019-09-11 18:40:46
3 D DW kinetics
DW mobility
Domain-Wall-Based Nanoelectronic Devices Challenges
scanning probe microscopy
nucleating spike domains
future DW-based nanoelectronic devices
electrical-field-biased 200 μ m
Lithium Niobate Single Crystals
LNO
4 orders
polarization P S
two-port DW-based nanoswitch
CSHG
Nanoscale Ferroelectric Domain Wall Dynamics
Real-Time 3 D Imaging
h 2h domain walls
spike domain formation
DWC