Self-organized Domain Structures Research Articles

The Formation of Self-Organized Domain Structures at Non-Polar Cuts of Lithium Niobate as a Result of Local Switching by an SPM Tip.

We have studied experimentally the interaction of isolated needle-like domains created in an array via local switching using a biased scanning probe microscope (SPM) tip and visualized via piezoelectric force microscopy (PFM) at the non-polar cuts of MgO-doped lithium niobate (MgOLN) crystals. It has been found that the domain interaction leads to the intermittent quasiperiodic and chaotic behavior of the domain length in the array in a manner similar to that of polar cuts, but with greater spacing between the points of bias application and voltage amplitudes. It has also been found that the polarization reversal at the non-polar cuts and domain interaction significantly depend on humidity. The spatial distribution of the surface potential measured by Kelvin probe force microscopy in the vicinity of the charged domain walls revealed the decrease of the domain length as a result of the partial backswitching after pulse termination. The phase diagram of switching behavior as a function of tip voltage and spacing between the points of bias application has been plotted. The obtained results provide new insight into the problem of the domain interaction during forward growth and can provide a basis for useful application in nanodomain engineering and development of non-linear optical frequency converters, data storage, and computing devices.

Formation of self-organized domain structures with charged domain walls in lithium niobate with surface layer modified by proton exchange

We have studied the self-organized dendrite domain structures appeared as a result of polarization reversal in the uniform field in lithium niobate single crystals with the artificial surface layer created by proton exchange. We have revealed the self-organized sub-micron scale dendrite domain patterns consisting of domain stripes oriented along the X crystallographic directions separated by arrays of dashed residual domains at the surface by scanning probe microscopy. Raman confocal microscopy allowed visualizing the quasi-regular dendrite domain structures with similar geometry in the vicinity of both polar surfaces. The depth of the structure was about 20 μm for Z+ polar surface and 70 μm for Z− one. According to the proposed mechanism, the dendrite structure formation at the surface was related to the ineffective screening of the residual depolarization field. The computer simulation of the structure formation based on the cellular automata model with probabilistic switching rule proved the eligibility of the proposed scheme, the simulated dendrite domain patterns at various depths being similar to the experimental ones.

Formation of the nanodomain structures after pulse laser heating in lithium tantalate: experiment and computer simulation

ABSTRACTFormation of the micro- and nanodomain structures in congruent lithium tantalate single crystal under the action of pyroelectric field induced by pulse infrared laser irradiation at elevated temperatures was investigated. Three types of the self-organized domain structures were obtained: (1) the self-similar domain structure formed in crystal regions heated below Curie temperature, (2) the maze-type domain structure, and (3) irregular-shaped isolated domains formed in the regions heated above Curie temperature. The results of calculation of the time dependent spatial distribution of the temperature and pyroelectric field have been used for explanation of the peculiarities of domain structure formation.

Self-Organized Nanodomain Structures Arising in Lithium Tantalate and Lithium Niobate after Pulse Heating by Infrared Laser

Formation of nanodomain structures during cooling after pulse heating by infrared laser has been studied in congruent lithium tantalate (CLT) and lithium niobate (CLN) single crystals. In situ study of the domain structure evolution allowed to reveal that in CLN the isolated domains appeared at the edges of the irradiated zone and grew to the center. In contrast, the quasi-regular stripe domain structure appeared in CLT near the edge of irradiated zone. The difference has been attributed to lower Curie temperature and larger pyroelectric coefficient of CLT. The self-organized domain structures can be used for periodical poling with submicron periods.

Micro- and Nanodomain Structures Produced by Pulse Laser Heating in Congruent Lithium Tantalate

Formation of the micro- and nanodomain structures under the action of pyroelectric field induced by pulse IR laser heating was studied in congruent lithium tantalate. Two types of the self-organized domain structures were found. The three-dimensional maze-type structure with average period about 100 nm appeared in the central part of the irradiated zone heated above Tc. The self-similar structure of oriented domain rays with nanoscale width formed at the edge of the irradiated zone. The obtained increase of the average distance between the nanodomain rays for irradiation at the elevated temperatures was attributed to the decrease of the pyroelectric field.

Formation of dendrite domain structures in stoichiometric lithium niobate at elevated temperatures

Formation of the dendrite-type self-organized domain structures during polarization reversal at elevated temperatures (above 230 °C) has been revealed and studied in stoichiometric lithium niobate LiNbO3 single crystals. Optical, confocal Raman, scanning electron, and piezoelectric force microscopy have been used for domain visualization. It has been shown experimentally that formation of the dendrite-like structures has been attributed to correlated nucleation caused by a field distribution in the vicinity of the charged domain walls.

Effect of phase composition (%) in the self-organization of a domain structure in FeNi films with quantum well thickness deposited at an angle in vacuum

The effect of the phase composition of FeNi films of quantum well thickness obliquely deposited in vacuum with an oblique anisotropy on the character of self-organized domain structures is investigated. The dependence of magnetoelastic and elastic constants on the phase composition of films is revealed.

Origin of periodic domain structure in Er 3+-doped β′-(Sm,Gd) 2(MoO 4) 3 crystal lines patterned by laser irradiations in glasses

Er 3+-doped β′-(Sm,Gd) 2(MoO 4) 3 crystal lines are patterned on the surface of Er 2O 3–Gd 2O 3–Sm 2O 3–MoO 3–B 2O 3 glasses by continuous-wave Yb:YVO 4 laser irradiations (wavelength: 1080 nm, power: 1.3 W, scanning speeds: 5 μm/s), and the origin of the periodicity of self-organized domain structures with high and low refractive index regions in crystal lines is examined from polarized optical microscope (POM) observations, micro-Raman scattering spectrum, and photoluminescence spectrum measurements. It is found that the periodicity of domain structures changes largely depending on Er 2O 3 content, i.e., the length of high (bright color in POM observations) and low (dark color) refractive index regions increases with increasing Er 2O 3 content and homogeneous crystal lines with no periodic domain structures are patterned in Er 2O 3–Sm 2O 3–MoO 3–B 2O 3 glass with no Gd 2O 3. Considering that the degree of ferroelasticities in β′-(Sm,Gd) 2(MoO 4) 3 crystals decreases due to the incorporation of Er 3+ ions, it is demonstrated that the origin of periodic domain structures in laser-patterned lines is due to spontaneous strains in ferroelastic β′-(Sm,Gd) 2(MoO 4) 3 crystals.