scholarly journals DOMAIN STRUCTURE AND SOME PROPERTIES OF RARE-EARTH GRANITE FERRITES

2020 ◽  
Vol 4 (3) ◽  
pp. 3-9
Author(s):  
Mirzogid Islomovich Daminov ◽  
◽  
Mirzo Zokirovich Sharipov ◽  
Rustam Khalilovich Shamsiev ◽  
Dilshod Ergashovich Khaitov ◽  
...  
Keyword(s):  
Rare Earth ◽  
Domain Structure ◽  
Crystallographic Orientation ◽  
Domain Walls ◽  
Spontaneous Magnetization ◽  
Magnetization Vector ◽  
Complex Domain ◽  
Cubic Symmetry ◽  
Domain Configuration

The crystals of rare-earth garnet ferrites have a complex domain structure, the form of which substantially depends on the crystallographic orientation of the under study sample. Due to the cubic symmetry of rare-earth garnet ferrites, 70, 110, and 180-degree domains can exist in them, and depending on the crystallographic orientation of the sample, the spontaneous magnetization vector in the realized domain configuration can lie in the plane of the sample (“Cotton” domains) perpendicular to the plane of the sample ("Faraday" domains), and make up a certain angle with its plane. According to known data, in all cases, the boundaries between neighboring domains in rare-earth garnet ferrites are the domain walls of the Bloch type

scholarly journals The Microstructural Model of the Ferromagnetic Material Behavior in an External Magnetic Field

2021 ◽  
Vol 7 (1) ◽  
pp. 7
Author(s):  
Anatoli A. Rogovoy ◽  
Oleg V. Stolbov ◽  
Olga S. Stolbova
Keyword(s):  
Magnetic Field ◽  
External Magnetic Field ◽  
Domain Walls ◽  
Magnetic Energy ◽  
Spontaneous Magnetization ◽  
Magnetization Vector ◽  
Ferromagnetic Material ◽  
Extremum Problem ◽  
Material Behavior ◽  
Anisotropy Axis

In this paper, the behavior of a ferromagnetic material is considered in the framework of microstructural modeling. The equations describing the behavior of such material in the magnetic field, are constructed based on minimization of total magnetic energy with account of limitations imposed on the spontaneous magnetization vector and scalar magnetic potential. This conditional extremum problem is reduced to the unconditional extremum problem using the Lagrange multiplier. A variational (weak) formulation is written down and linearization of the obtained equations is carried out. Based on the derived relations a solution of a two-dimensional problem of magnetization of a unit cell (a grain of a polycrystal or a single crystal of a ferromagnetic material) is developed using the finite element method. The appearance of domain walls is demonstrated, their thickness is determined, and the history of their movement and collision is described. The graphs of distributions of the magnetization vector in domains and in domain walls in the external magnetic field directed at different angles to the anisotropy axis are constructed and the magnetization curves for a macrospecimen are plotted. The results obtained in the present paper (the thickness of the domain wall, the formation of a 360-degree wall) are in agreement with the ones available in the current literature.

The need of electron microscopy in the study of domains and domain walls in ferroelectrics

1994 ◽  
Vol 52 ◽  
pp. 550-551
Author(s):  
Wenwu Cao
Keyword(s):  
Domain Wall ◽  
Domain Walls ◽  
High Mobility ◽  
Continuum Theory ◽  
Polarization Vector ◽  
Ferroelectric Materials ◽  
Dielectric Constants ◽  
Nonlocal Coupling ◽  
Cubic Symmetry ◽  
Gradient Energy

Domain structures play a key role in determining the physical properties of ferroelectric materials. The formation of these ferroelectric domains and domain walls are determined by the intrinsic nonlinearity and the nonlocal coupling of the polarization. Analogous to soliton excitations, domain walls can have high mobility when the domain wall energy is high. The domain wall can be describes by a continuum theory owning to the long range nature of the dipole-dipole interactions in ferroelectrics. The simplest form for the Landau energy is the so called ϕ model which can be used to describe a second order phase transition from a cubic prototype,where Pi (i =1, 2, 3) are the components of polarization vector, α's are the linear and nonlinear dielectric constants. In order to take into account the nonlocal coupling, a gradient energy should be included, for cubic symmetry the gradient energy is given by,

Observation of complex domain walls in KTiOPO4

1988 ◽  
Vol 53 (16) ◽  
pp. 1498-1499 ◽  
Author(s):  
G. M. Loiacono ◽  
R. A. Stolzenberger
Keyword(s):  
Domain Walls ◽  
Complex Domain

The effect of Dzyaloshinskii–Moriya interaction on direct and backward transition between magnetic states of Pt/Co/Ir/Co/Pr synthetic ferrimagnet

2021 ◽  
Vol 6 (3) ◽  
pp. 167-178
Author(s):  
Artem D. Talantsev ◽  
Ekaterina I. Kunitsyna ◽  
Roman B. Morgunov
Keyword(s):  
Thin Layer ◽  
Domain Structure ◽  
Magnetization Reversal ◽  
Domain Walls ◽  
Ferromagnetic Layers ◽  
Magneto Optical Kerr Effect ◽  
Magnetic States ◽  
Fluctuation Fields ◽  
Moriya Interaction ◽  
Effect Technique

In this paper, we present the study of domain structure accompanying interstate transitions in Pt/Co/Ir/Co/Pr synthetic ferrimagnet (SF) of 1.1 nm thick and 0.6 – 1.0 nm thin ferromagnetic Co layers. Variation in the thickness of the thin layer causes noticeable changes in the domain structure and mechanism of magnetization reversal revealed by MOKE (Magneto-Optical Kerr Effect) technique. Magnetization reversal includes coherent rotation of magnetization of the ferromagnetic layers, generation of magnetic nuclei, spreading of domain walls (DW), and development of areas similar with strip domains, dependently on thickness of the thin layer. Inequivalence of the direct and backward transitions between magnetic states of SF with parallel and antiparallel magnetizations was observed in sample with thin layer thicknesses 0.8 nm and 1.0 nm. Asymmetry of the transition between these states is expressed in difference fluctuation fields and shapes of reversal magnetization nucleus contributing to the correspondent forward and backward transitions. We proposed simple model based on asymmetry of Dzyaloshinskii–Moriya interaction. This model explains competition between nucleation and domain wall propagation due to increase/decrease of the DW energy dependently on direction of the spin rotation into the DW in respect to external field.

scholarly journals Lattice Location of Rare Earth Ions in Semiconductors: Interpretation and Limitations of Using g Values

2005 ◽  
Vol 866 ◽  
Author(s):  
David Carey
Keyword(s):  
Rare Earth ◽  
Crystal Field ◽  
Field Potential ◽  
Rare Earth Ions ◽  
Lattice Location ◽  
Paramagnetic Resonance ◽  
Cubic Symmetry ◽  
Crystal Fields ◽  
Valid Comparison ◽  
G Value

AbstractThe g values of rare earth ions obtained from either paramagnetic resonance or Zeeman measurements are often used to interpret the location and/or environment surrounding rare earth ions. In the case of centres with cubic symmetry the g value can be used to distinguish between substitutional and interstitial sites. For centres with less than cubic symmetry the average g value, taken as 1/3 trace of the g tensor, is often used as an indication of the lattice location and/or a measure of the strength of the local crystal field. This approach is widely used but is based on the assumption that the non-cubic terms in the total crystal field potential are small compared with the cubic crystal field. In this paper we have explored this assumption by calculating the principal g values in axial crystal fields for the Er3+ ion. We examine the limits over which the average g value approach is valid. Comparison is made with published results.

scholarly journals High-Throughput Screening of Rare-Earth-Lean Intermetallic 1-13-X Compounds for Good Hard-Magnetic Properties

Metals ◽  
2019 ◽  
Vol 9 (10) ◽  
pp. 1096 ◽  
Author(s):  
Georg Krugel ◽  
Wolfgang Körner ◽  
Daniel F. Urban ◽  
Oliver Gutfleisch ◽  
Christian Elsässer
Keyword(s):  
Rare Earth ◽  
High Throughput ◽  
High Throughput Screening ◽  
Spontaneous Magnetization ◽  
Anisotropy Field ◽  
Structure Type ◽  
Anisotropy Constant ◽  
Maximum Energy ◽  
Maximum Energy Product ◽  
Energy Product

By computational high-throughput screening, the spontaneous magnetization M s , uniaxial magnetocrystalline anisotropy constant K 1 , anisotropy field H a , and maximum energy product ( B H ) max are estimated for ferromagnetic intermetallic phases with a tetragonal 1-13-X structure related to the LaCo 9 Si 4 structure type. For SmFe 13 N, a ( B H ) max as high as that of Nd 2 Fe 14 B and a comparable K 1 are predicted. Further promising candidates of composition SmFe 12 AN with A = Co, Ni, Cu, Zn, Ga, Ti, V, Al, Si, or P are identified which potentially reach (BH) max values higher than 400 kJ/m 3 combined with significant K 1 values, while containing almost 50% less rare-earth atoms than Nd 2 Fe 14 B.

scholarly journals Domain Diversity and Polarization Switching in Amino Acid β-Glycine

Materials ◽  
2019 ◽  
Vol 12 (8) ◽  
pp. 1223 ◽  
Author(s):  
Daria Vasileva ◽  
Semen Vasilev ◽  
Andrei L. Kholkin ◽  
Vladimir Ya. Shur
Keyword(s):  
Amino Acid ◽  
Domain Structure ◽  
Lead Zirconate Titanate ◽  
Domain Walls ◽  
Piezoelectric Materials ◽  
Polarization Switching ◽  
Building Blocks ◽  
Crystallographic Structure ◽  
Processing Temperature ◽  
Sensors And Actuators

Piezoelectric materials based on lead zirconate titanate are widely used in sensors and actuators. However, their application is limited because of high processing temperature, brittleness, lack of conformal deposition and, more importantly, intrinsic incompatibility with biological environments. Recent studies on bioorganic piezoelectrics have demonstrated their potential in these applications, essentially due to using the same building blocks as those used by nature. In this work, we used piezoresponse force microscopy (PFM) to study the domain structures and polarization reversal in the smallest amino acid glycine, which recently attracted a lot of attention due to its strong shear piezoelectric activity. In this uniaxial ferroelectric, a diverse domain structure that includes both 180° and charged domain walls was observed, as well as domain wall kinks related to peculiar growth and crystallographic structure of this material. Local polarization switching was studied by applying a bias voltage to the PFM tip, and the possibility to control the resulting domain structure was demonstrated. This study has shown that the as-grown domain structure and changes in the electric field in glycine are qualitatively similar to those found in the uniaxial inorganic ferroelectrics.

Observations of Domain Structure at Initial Growth Stage of PbTiO3 Thin Films Grown by Mocvd

1999 ◽  
Vol 596 ◽  
Author(s):  
H. Fujisawa ◽  
M. Shimizu ◽  
H. Niu ◽  
K. Honda ◽  
S Ohtani
Keyword(s):  
Thin Films ◽  
Domain Structure ◽  
Growth Stage ◽  
Domain Walls ◽  
Chemical Vapor ◽  
Initial Growth ◽  
Continuous Film ◽  
Cross Sectional ◽  
Initial Growth Stage ◽  
Transmission Electron

AbstractDomain structure and growth mechanism of PbTiO3 thin films were investigated using a transmission electron microscopy(TEM) from the viewpoint of size effects. At initial growth stage of (111)-oriented PbTiO3 films prepared by metalorganic chemical vapor deposition(MOCVD), triangle-shaped islands were grown on Pt(111)/SiO2/Si before becoming a continuous film. Triangular islands grew gradually in a lateral dimension. This means that PbTiO3 films grew two-dimensionally at initial growth stage. In cross-sectional TEM photomicrographs, (101)-twin boundaries (90° domain walls) and inclination of {110} or {101}-plane were observed in PbTiO3 islands. This result indicates that such small PbTiO3 islands have a tetragonal structure and could have spontaneous polarization. The minimum island which had 90° domain walls was 10nm high and 18nm wide.

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