Local polarization reversal in KTP single crystals

The research was made possible in part by RFBR (grant 16-02-00724) and by President of Russian Federation grant for young scientists (Contract 14.Y30.17.2837-MK). The equipment of the Ural Center for Shared Use “Modern nanotechnology” Ural Federal University was used

As-Grown Domain Structure in Calcium Orthovanadate Crystals

An as-grown domain structure in nominally pure and Mn-doped calcium orthovanadate (CVO) crystals was studied by several methods of domain imaging: optical microscopy, piezoelectric force microscopy, and Cherenkov-type second harmonic generation. The combination of imaging methods provided an opportunity for comprehensive study of the domain structure on the polar surface and in the bulk of the samples. It was shown that, in nominally pure CVO crystals, an irregular 3D maze of rounded domains, with charged walls, essentially tilted from the polar direction, was present. It was proposed that the domain structure was formed just below the phase transition temperature and persisted during subsequent cooling. Such behavior is due to effective bulk screening of the depolarization field and a low value of the pyroelectric field which appears during cooling. The revealed formation of triangular domains and flat fragments of domain walls in Mn-doped CVO was attributed to polarization reversal under the action of the polar component of the pyroelectric field, above the threshold value for domain switching. This fact represents the first observation of the domain switching in CVO crystals. © 2021 by the authors. Licensee MDPI, Basel, Switzerland.Funding: This research was funded by the Russian Foundation for Basic Research, grant number 20-02-00588-a, and the Ministry of Science and Higher Education of the Russian Federation, grant numbers 075-15-2021-677 and FEUZ-2020-0054

Polarization reversal in KTP single crystals with surface dielectric layer and at elevated temperatures

The research was made possible in part by Government of the Russian Federation (Act 211, Agreement 02.A03.21.0006) by RFBR (grant 16-02-00724), and by President of Russian Federation grant for young scientists (Contract 14.Y30.17.2837-MK). The equipment of the Ural Center for Shared Use “Modern nanotechnology” Ural Federal University was used

The role of humidity on the domain growth during local switching in RKTP single crystals

The equipment of the Ural Center for Shared Use “Modern Nanotechnology” UrFU was used. This research was made possible in part by President of Russian Federation Grant for young scientists (grant No. МК-1217.2019.2)

Polarization reversal in Rb:KTP and KTA single crystals

The equipment of the Ural Center for Shared Use “Modern nanotechnology” Ural Federal University was used. This research was made possible in part by President of Russian Federation Grant for young scientists (grant No. МК-1217.2019.2)

Forward growth of ferroelectric domains with charged domain walls. Local switching on non-polar cuts

Forward domain growth representing one of the main stages of domain switching is studied for isolated domains and domain arrays appearing as a result of tip-induced switching on the non-polar cuts of lithium niobate crystals. Formation of the wedge-like domains with a high aspect ratio and charged domain walls is observed. The domain growth in the area with a negligible external field is considered in terms of the kinetic approach based on analogy with crystal growth. The domain wall motion by step generation and propagation of the charged kinks is discussed. It is proposed that the switching field contains the inputs of the external field produced by a biased scanning probe microscope tip, the depolarization field produced by charged kinks, and the screening fields. According to the simulation results of the field distribution, the forward growth is caused by the step generation near the tip and the kink propagation induced by the depolarization field produced by the kinks. Scanning with the biased tip creates self-assembled domain arrays with several modes of domain length alteration: doubling, quadrupling, and chaotic. The statistical characterization of the arrays proves their high ordering. The array is formed under the influence of the depolarization field produced by three neighboring domains. The proposed mechanism can be applied for forward domain growth during switching on the polar cuts as well. In this case, the steps on the domain wall are generated on the polar surface, whereas the domain elongates by kink motion in the field produced by the charged kinks. © 2021 Author(s).The equipment of the Ural Center for Shared Use “Modern nanotechnology” Ural Federal University was used. The research was made possible by the Russian Science Foundation (Project No. 19-12-00210)

Kinetics of domain structure in KTiOPO4 crystals

The equipment of the Ural Center for Shared Use “Modern Nanotechnology” UrFU was used. The research was made possible by RFBR (16-02-00724 a) and by Government of the Russian Federation (Act 211, Agreement 02.A03.21.0006)

Domain wall orientation and domain shape in KTiOPO4 crystals

Domain shape evolution and domain wall motion have been studied in KTiOPO4 (KTP) ferroelectric single crystals using complementary experimental methods. The in situ visualization of domain kinetics has allowed revealing: (1) qualitative change of the domain shape, (2) dependence of the domain wall velocity on its orientation, (3) jump-like domain wall motion caused by domain merging, (4) effect of domain shape stability. The model of domain wall motion driven by generation of elementary steps (kink-pair nucleation) and subsequent kink motion is presented. The decrease in the relative velocity of the approaching parallel domain walls is attributed to electrostatic interaction. The effect of polarization reversal induced by chemical etching is observed. The obtained results are important for the development of domain engineering in the crystals of KTP family. Published by AIP Publishing

STUDY OF DOMAIN STRUCTURE EVOLUTION AND SWITCHING CURRENT ANALYSIS IN KTiOPO4 SINGLE CRYSTALS

We present a detailed study of the domain kinetics and an analysis the switching currents in KTiOPO4 (KTP) single crystals. The domain shape evolution was studied by in situ optical visualization supplemented by visualization of the static domain structures with high spatial resolution. Two stages of the polarization reversal have been distinguished during analysis of the switching current data. The first stage fitted by Kolmogorov-Avrami formula. The second stage with spikes in the switching current caused was analyzed by a modified Korcak method.Работа выполнена с использованием оборудования УЦКП «Современные нанотехнологии» УрФУ, при финансовой поддержке Минобрнауки РФ (Act 211, Согл. 02.A03.21.0006), РФФИ (Гр. 16-02-00724-a) и гранта Президента Российской федерации для молодых ученых (договор №14.Y30.17.2837-МК)

In situ study of domain structure kinetics in single crystals of potassium titanyl-phosphate

Проведено экспериментальное исследование формы доменов и кинетики доменной структуры в монокристаллах титанил-фосфата калия (KTiOPO4, KTP) с использованием взаимодополняющих методов. С помощью in situ визуализации высокого разрешения выявлено три типа доменных стенок с существенно различающейся скоростью движения. Для объяснения полученных эффектов предложена модель движения доменных стенок за счет генерации элементарных ступеней и движения кинков.The domain shape and domain kinetics has been studied by experimentally in potassium titanyl phosphate (KTiOPO4, KTP) using complementary experimental methods. Three types of moving domain walls with essentially different velocities were revealed using the high temporal resolution in situ visualization of domain structure. The model of domain wall motion as a result of steps generation and kink motion has been proposed for the explanation of obtained experimental results.Работа выполнена с использованием оборудования УЦКП «Современные нанотехнологии» УрФУ, при финансовой поддержке Министерства образования и науки РФ (акт 211, соглашение 02.A03.21.0006, Государственное задание на 2017-2019 №3.4993.2017/6.7, № 3.4973.2017/7.8), РФФИ (Грант 16-02-00724-a) и гранта Президента РФ для молодых ученых (договор №14.Y30.17.2837-МК)