Ultrathin films of ferroelectric solid solutions under residual depolarizing field

A first-principles-derived approach is developed to study the effects of uncompensated depolarizing electric fields on the properties of Pb(Zr,Ti)O$_3$ ultrathin films for different mechanical boundary conditions. A rich variety of ferroelectric phases and polarization patterns is found, depending on the interplay between strain and amount of screening of surface charges. Examples include triclinic phases, monoclinic states with in-plane and/or out-of-plane components of the polarization, homogeneous and inhomogeneous tetragonal states, as well as, peculiar laminar nanodomains.Comment: REVTeX, 7 pages, 2 figures, fig 2 in colo

Domain evolution of BaTiO3 ultrathin films under electric field: a first-principles study

A first-principles-derived method is used to study the morphology and electric-field-induced evolution of stripe nanodomains in (001) BaTiO3 (BTO) ultrathin films, and to compare them with those in (001) Pb(Zr,Ti)O3 (PZT) ultrathin films. The BaTiO3 systems exhibit 180o periodic stripe domains at null electric field, as in PZT ultrathin films. However, the stripes alternate along [1-10] in BTO systems versus [010] in PZT systems, and no in-plane surface dipoles occur in BTO ultrathin films (unlike in PZT materials). Moreover, the evolution of the 180o stripe domains in the BaTiO3 systems, when applying and increasing an electric field along [001], involves four regions: Region I for which the magnitude of the down dipoles (i.e., those that are antiparallel to the electric field) is reduced, while the domain walls do not move; Region II in which some local down dipoles adjacent to domain walls switch their direction, resulting in zigzagged domain walls - with the overall stripe periodicity being unchanged; Region III in which nanobubbles are created, then contract along [110] and finally collapse; and Region IV which is associated with a single monodomain. Such evolution differs from that of PZT ultrathin films for which neither Region I nor zigzagged domain walls exist, and for which the bubbles contract along [100]. Discussion about such differences is provided.Comment: 19 pages, 4 figures, 27 references, submitted to Phys. Rev.

Properties of Pb(Zr,Ti)O3_3 ultrathin films under stress-free and open-circuit electrical boundary conditions

A first-principles-based scheme is developed to simulate properties of (001) PbO-terminated Pb(Zr$_{1-x}$Ti$_{x}$)O$_3$ thin films that are under stress-free and open-circuit boundary conditions. Their low-temperature spontaneous polarization never vanishes down to the minimal thickness, and continuously rotates between the in-plane and directions when varying the Ti composition around x=0.50. Such rotation dramatically enhances piezoelectricity and dielectricity. Furthermore, the order of some phase transitions changes when going from bulk to thin films.Comment: 11 pages, 3 figure

Phase diagram of Pb(Zr,Ti)O3 solid solutions from first principles

A first-principles-derived scheme, that incorporates ferroelectric and antiferrodistortive degrees of freedom, is developed to study finite-temperature properties of PbZr1-xTixO3 solid solutions near its morphotropic phase boundary. The use of this numerical technique (i) resolves controversies about the monoclinic ground-state for some Ti compositions, (ii) leads to the discovery of an overlooked phase, and (iii) yields three multiphase points, that are each associated with four phases. Additional neutron diffraction measurements strongly support some of these predictions.Comment: 10 pages, 2 figure

Магия и власть (технологические основы)

The authors of the article examine historical regularities in the evolution of power technologies in the context of non-positivistic philosophical ideas of the 20th century. These philosophical beliefs imply an intuitive understanding of power, deal with the formation of psychological mechanisms of the domination-subordination relations and describe their development. The authors pay special attention to magical and sacred aspects at the early stages of political development, as well as the subsequent formation of power structures and organization of administrative functions. At the present stage of social development, the digitalization of state and political activity is of great importance. The forming order of domination and subordination, as well as power relations, initially comprise magical elements allowing a person or a group of individuals to manipulate others' behavior. Modern digital technologies find their origins in centuries-long traditions either consciously or unconsciously. The need for managerial influence overcoming social chaos is objective. As a result, the state rationalizes the management of society, organizes its administrative functions and develops a more advanced technology of political power. However, people's dependence on technology is connected with decreasing interpersonal cooperation, growing individual dependence on power and other negative experiences. The modern humanities aim to determine regularities in the evolution of political power technologies and overcome the negative consequences of modern power technologization.El autor estudia las leyes históricas de la evolución de las tecnologías de poder en la tradición de las tendencias filosóficas no positivistas del siglo XX, que presuponen una comprensión intuitiva de la esencia del poder, prestan atención a la formación de mecanismos psicológicos de relaciones de poder y subordinación, la evolución de estas relaciones. Aquí son importantes los aspectos de lo mágico y lo sagrado en las primeras etapas del desarrollo político, la posterior formación de estructuras de poder y el diseño organizativo de las funciones administrativas. En la etapa actual del desarrollo de la sociedad, los procesos de digitalización del estado y la actividad política son fundamentales. El orden emergente de dominación y subordinación, las relaciones de poder son inherentemente inherentes a los elementos de la magia, permitiendo que uno o unos pocos manipulen el comportamiento de todos. Las tecnologías digitales modernas sacan consciente o inconscientemente su confianza en la tradición, perdida en el pasado distante. La necesidad de influencia gerencial para superar el caos social es objetiva. Posteriormente, el estado racionaliza la gestión de la sociedad, organiza funciones administrativas, crea una tecnología más avanzada de poder político. Pero la dependencia de la gente de la tecnología y la tecnología está acompañada por una disminución en la solidaridad interpersonal, un aumento en la dependencia de la persona del poder y experiencias negativas sobre esto. La tarea de las humanidades modernas se ve en la identificación de las leyes de la evolución de las tecnologías de poder político, en la superación de las consecuencias negativas de la moderna tecnologización del poder.Исследуются исторические закономерности эволюции властных технологий в традиции непозитивистских философских направлений ХХ в., которые предполагают интуитивное осмысление сущности власти, обращают внимание на формирование психологических механизмов отношений власти и подчинения, на эволюцию этих отношений. Здесь имеют значение аспекты магического и сакрального на ранних этапах политического развития, последующее формирование структур власти и организационное оформление управленческих функций. На современном этапе развития общества принципиальны процессы цифровизации государства и политической деятельности. Складывающемуся порядку господства и подчинения, властеотношениям изначально присущи элементы магического, позволяющие одному или немногим манипулировать поведением всех. Современные цифровые технологии сознательно или неосознанно черпают свою уверенность в традиции, теряющейся в далеком прошлом. Необходимость управленческого воздействия, преодолевающего социальный хаос, является объективной. Впоследствии государство рационализирует управление обществом, организационно оформляет управленческие функции, создает более совершенную технологию политической власти. Но зависимость людей от техники и технологии сопровождается уменьшением межличностной солидарности, увеличением зависимости человека от власти, негативными переживаниями по этому поводу. Задача современной гуманитарной науки видится в выявлении закономерностей эволюции технологий политической власти, в преодолении негативных последствий современной технологизации власти

Asymmetric dipolar ring

Describes a device having a dipolar ring surrounding an interior region that is disposed asymmetrically on the ring. The dipolar ring generates a toroidal moment switchable between at least two stable states by a homogeneous field applied to the dipolar ring in the plane of the ring. The ring may be made of ferroelectric or magnetic material. In the former case, the homogeneous field is an electric field and in the latter case, the homogeneous field is a magnetic field

Ferroelectric nanostructure having switchable multi-stable vortex states

A ferroelectric nanostructure formed as a low dimensional nanoscale ferroelectric material having at least one vortex ring of polarization generating an ordered toroid moment switchable between multi-stable states. A stress-free ferroelectric nanodot under open-circuit-like electrical boundary conditions maintains such a vortex structure for their local dipoles when subject to a transverse inhomogeneous static electric field controlling the direction of the macroscopic toroidal moment. Stress is also capable of controlling the vortex\u27s chirality because of the electromechanical coupling that exists in ferroelectric nanodots