Unusual polarization patterns in flat epitaxial ferroelectric nanoparticles

Interest in epitaxial ferroelectric nanoislands was growing rapidly in recent years driven by their potential for devices, especially ultradense memories. Recent advances in the "bottom- up" (self-assembly) nanometer scale techniques have opened up the opportunities of fabricating high-quality epitaxial ferroelectric nanoislands with extremely small thickness and lateral size on the order of 1 nm and 20 nm, respectively. On the other hand, recent emergence of powerful probes, such as piezoresponse force microscopy (PFM), has enabled imaging of a local domain structure with sub-10 nm resolution. In spite of those developments, a clear understanding of the polarization patterns in epitaxial ferroelectric nanoislands is lacking, and some important characteristics, like a critical lateral size for ferroelectricity, are not yet established. Here, we perform ab-initio studies of non-electroded epitaxial Pb(Zr0.5Ti0.5)O3 and BaTiO3 nanoislands and show the existence of novel polarization patterns driven by the misfit strains and/or anisotropy energy. The results allow interpretation of the data and design of the ferroelectric nanostructures with tailored response to external field.Comment: 7 pages, 7 figure

CHARACTERISTICS OF THE LEGAL FOUNDATIONS OF THE MILITARY MEDICAL EXAMINATION IN THE TROOPS OF THE NATIONAL GUARD OF THE RUSSIAN FEDERATION

Background. At present, due to political, military-technical, socio-economic and organizational factors, the organization of medical support for military personnel (employees) and their families is an urgent task for scientists and practitioners. An important direction in the provision of social guarantees in the field of medical support is the conduct of a military medical examination of military personnel and members of their families to resolve issues of determining the category of fitness for military service, establishing a causal relationship, resolving issues of the possibility of living in certain areas and resolving other issues. Materials and research methods. The theoretical and methodological basis of the study was the authors’ reliance on systematic, comparative legal and integrated approaches. To achieve the goal and solve the problems of the study, the authors used a set of modern methods for cognizing the phenomena of social and legal reality: systemic, interdisciplinary and complex analysis and synthesis of its results, conceptualization, abstraction, analogy, deductive and comparative legal methods and theoretical generalizations. Results and conclusions. The article discusses the content of the legal framework for the implementation of military medical expertise in the troops of the National Guard of the Russian Federation. Characteristics of the constitutional norms and norms of federal legislation in the field of military medical expertise are given, characterizing the requirements of regulatory legal acts that regulate these legal relations are considered. Individual legal and technical inaccuracies are pointed out, which can be improved by bringing departmental documents in line with acts of a higher power. The results of the study can be used when writing scientific papers in the field of medical and military law, as well as in the pedagogical process in the implementation of educational programs in the organization of healthcare and in the field of jurisprudence

Vortex-to-Polarization Phase Transformation Path in Pb(ZrTi)O3_3 Nanoparticles

Phase transformation in finite-size ferroelectrics is of fundamental relevance for understanding collective behaviors and balance of competing interactions in low-dimensional systems. We report a first-principles effective Hamiltonian study of vortex-to-polarization transformation in Pb(Zr$_{0.5}$Ti$_{0.5}$)O$_3$ nanoparticles, caused by homogeneous electric fields normal to the vortex plane. The transformation is shown to (1) follow an unusual {\it macroscopic} path that is symmetry non-conforming and characterized by the occurrence of a previously unknown structure as the bridging phase; (2) lead to the discovery of a striking collective phenomenon, revealing how ferroelectric vortex is annihilated {\it microscopically}. Interactions underlying these behaviors are discussed