Calculation of magnetocrystalline anisotropy energy in ndco5. Intrinsic threshold current density of domain wall motion in. Using densityfunctional theory, we have calculated the magnetization and magnetocrystalline anisotropy at zero temperature for a range of compositions. Highfield cantilever magnetometry as a tool for the determination of the magnetocrystalline anisotropy of single crystals fatima martinhernandeza. The coterminated cofe thin film shows two total energy minima. Magnetocrystalline anisotropy mca, which is mainly. Lodestones were of vital importance to navigation for making compasses, described by alexander neckam, an englishman, in about ad 1200.
Magnetocrystalline anisotropy and magnetization reversal in. Relation between bandstructure and magnetocrystalline. In this study coterminated and feterminated 5layer cofe thin films are employed. We find the strain or selenium vacancy vse alone cannot induce the magnetism. Influence of mn substitution on crystal structure and. The magnetic configuration in polycrystalline bafe12o19 nanoslice is a curling structure, revealing that the effect of magnetocrystalline anisotropy in uniaxial magnetic nanomaterials can be broken by forming an amorphous structure or polycrystalline structure with tiny grains. If the easy axis is in the direction, the anisotropy energy can be expressed as one of the forms. Introduction acoustic noise generated by power transformers has. Effect of induced shape anisotropy on magnetic properties of ferromagnetic cobalt nanocubes d. Generally, the existence of an orbital magnetic moment and a strong spinorbit interaction is a necessary prerequisite for the magnetocrystalline anisotropy mechanisms. It determines stable direction of the orbital magnetization. The cef breaks symmetry of the space for the f electrons. Magnetocrystalline anisotropy an overview sciencedirect.
A magnetic particle with uniaxial anisotropy has one easy axis. Carrying out a micromagnetic simulation, we revealed that the intrinsic threshold current density decreases with decreases in the strip thickness, width, and magnetization, whereas it did not depend significantly on magnetocrystalline anisotropy and exchange stiffness. However, an interplay between strain and vse leads to the magnetism due to the breaking of ptpt metallic bonds. These results showed good agreement with onedimensional 1d analysis. The energy associated with magnetic anisotropy can depend on the direction cosines in various ways, the most common of which are discussed below. The magnetocrystalline anisotropy energy mae of ndco 5 was studied from first principles using the full potential linearized augmented plane wave flapw method. Giant magnetocrystalline anisotropy of 5d transition metal. The mca is manifested by the fact that the energy of a magnetically ordered material depends on the direction of the magnetization m with respect to the crystal lattice. Shape anisotropy, which originates from the dipoledipole interactions that occur in ferromagnets. Pdf magnetocrystalline anisotropy of d03fe3si from first. If there was no other energy term, the magnetization would always vanish in zero applied field. The second order arises due to the mutual interaction of the magnetic dipoles. Magnetocrystalline anisotropy is a phenomenon in which the internal energy magnetic anisotropy energy varies by the.
E is roughly proportional to the power of the longrange order parameter s, i. Development of magnetic order in the tbnial,in series and magnetocrystalline anisotropy in tbtxcompounds m. Spinotherorbit interaction and magnetocrystalline anisotropy. In physics, a ferromagnetic material is said to have magnetocrystalline anisotropy if it takes. Anisotropy is also of considerable practical importance because it is exploited in the design of most magnetic materials of commercial importance. Influence of mn substitution on crystal structure and magnetocrystalline anisotropy of nanocrystalline co1. Firstprinciples calculations of the magnetocrystalline. Secret is magnetic anisotropy energy certain directions within crystal are at lower energy than others how does that net magnetization get frozen in so that we may measure it at some later time. The magnetic anisotropy in the oriented ceramics is demonstrated to be caused by the magnetocrystalline anisotropy with the easy magnetization direction along the c. This interaction is long range and so its contribution is dependent upon the shape of the sample. Firstprinciples calculations of magnetocrystalline. Direct observation of magnetocrystalline anisotropy tuning. Determination of magnetic anisotropy constants in fe ultrathin film.
Generally, the existence of an orbital magnetic moment and a strong spinorbit interaction is a necessary prerequisite for the magnetocrystalline anisotropy. Magnetization, magnetocrystalline anisotropy and magnetostriction in some rareearthcobalt compounds, r2 c017. The magnetocrystalline anisotropy becomes weaker in the ceramics. Firstprinciples study of magnetocrystalline anisotropy and. Determination of magnetic anisotropy constants in fe. Fesi alloy, magnetic anisotropy field, magnetic domain, magnetocrystalline anisotropy, magnetostriction, singlecrystal film, soft magnetic material 1. The magnetic dipolar anisotropy, or shape anisotropy, is mediated by the dipolar interaction. Magnetic anisotropy strongly affects the shape of hysteresis loops and controls the coercivity and remanence. Theory of magnetocrystalline anisotropy springerlink.
A nonvanishing hall signal is observed over a broad temperature range, spanning the compensation temperature 155k, where the net magnetic moment is strictly zero, the anomalous hall conductivity is 66731 m. Pdf magnetism and magnetocrystalline anisotropy of cofe. Magnetocrystalline anisotropy energy for adatoms and monolayers on nonmagnetic substrates. The heisenberg hamiltonian is completely isotropic, and its energy levels do not depend on the direction in space in which the crystal is magnetized. Pdf random magnetocrystalline anisotropy in twophase. Aug 23, 2001 we report the effect of the twobody, spinotherorbit interaction on the magnetocrystalline anisotropy energy of the 3d transition metals. Matter 32 035801 view the article online for updates and enhancements.
The relevant energy differences were computed for bcc fe, fcc ni, and hcp co using the linearized augmented plane wave method to solve the kohnsham nist equations in the local spindensity approximation. The spinorbit interaction is the primary source of magnetocrystalline anisotropy. This compound was chosen as a prototype for investigating the cell boundary phase believed to play a key role in establishing the high coercivity of commercial smco 2. Random magnetocrystalline anisotropy in twophase nanocrystalline systems.
Giant magnetocrystalline anisotropy of 5d transition metalbased phthalocyanine sheet jian zhou,a qian wang,bca qiang sun,cba yoshiyuki kawazoed and puru jenaa large magnetocrystalline anisotropy energy mae is a critical requirement for nanomagnets for applications in magnetic memory and storage devices. The problem of the magnetocrystalline anisotropy energy mae. To get a reliable abinitio value for the magnetocrystalline anisotropy mca energy of fept, we employ the fullpotential linearized augmented plane. Such results are connected to their magnetocrystalline anisotropy, and to their complex magnetization reversal mode.
Magnetocrystalline anisotropy energy in cubic fe, co, and ni. However, real magnetic materials are not isotropic. Magnetic anisotropy an overview sciencedirect topics. We investigate magnetism and magnetocrystalline anisotropy of cofe thin films, using vasp code in gga. Magnetocrystalline anisotropy energy of fe001, fe110. The magnetocrystalline anisotropy of pristine and cosubstituted.
Puente orench2,3 1charles university, faculty of mathematics and physics, department of condensed matter physics, ke karlovu 5. Pdf firstprinciples calculations on the magnetocrystalline anisotropy mca. The horizontal axis is re and the vertical axis the deference of total energy between 4f site substitution and 4g site substitution. A large amount of research has been done in which the magnetocrystalline anisotropy energy for fcc ni and bcc fe was calculated based on the electronic structure of these elements. Pdf direct observation of magnetocrystalline anisotropy.
Pdf controlling the magnetocrystalline anisotropy of. We also discuss the relationship between the magnetocrystalline anisotropy energy and the orbital magnetic moment. In iron this is the 0,0,1 direction, whereas in nickel it is the 1,1,1 direction. In this context, the magnetocrystalline anisotropy is a consequence of the directional dependence of the energy of a d or fcharge cloud in the crystal field.
We present a computational study of the compound for 0. Anisotropy in films is a sum of contributions from the intrinsic magnetocrystalline anisotropy expected from the bulk equivalent material and a number of effects linked to the fact that the structure of a film is for many reasons not equivalent to the bulk. An analogous mechanism may account for the magnetocrystalline anisotropy in metallic 3d electron magnets gignoux and schmitt 1991. If the easy axis is in the direction, the anisotropy energy can be. It is an interesting phenomenon both for fundamental and technological reasons, as the mca is important among others.
We report the effect of the twobody, spinotherorbit interaction on the magnetocrystalline anisotropy energy of the 3d transition metals. Magnetocrystalline anisotropy energy of fe001, fe110 slabs and nanoclusters. The epitaxial growth of ultrathin fe film on si111 surface provides an excellent opportunity to investigate the contribution of magnetic anisotropy to magnetic behavior. The epsilon fe 2 o 3 phase of iron oxide has been studied to understand the spin structure and the magnetocrystalline anisotropy in the bulk and in thin films of. We report the observation of ferromagnetic resonance fmr and the determination of the magnetocrystalline anisotropy in 100oriented singlecrystalline thin. A bulk d0 nan of rocksalt or zincblende structure was predicted to be a ferromagnetic half metal and furthermore the halfmetallicity would be retained in thin films. Pdf uniaxial magnetocrystalline anisotropy of tetragonal. Development of magnetic order in the tbnial,in series and. Magnetocrystalline anisotropy in rareearth magnets mainly arises from the r4f electrons.
Hence shape anisotropy becomes important in thin films and often produces inplane alignment of. Theoretical study of the microscopic origin of magnetocrystalline anisotropy in fe 16 n 2 and its alloys. Magnetic fielddependent shape anisotropy in small patterned. Magnetocrystalline anisotropy and exchange probed by high. Magnetism and magnetocrystalline anisotropy in singlelayer. Magnetocrystalline anisotropy an overview sciencedirect topics. The free energy of the crystal thus contains a term which couples the magnetisation direction to the crystal lattice. Secret is that magnetic anisotropy energy can change from low, allowing magnetization to come into. Analysis of the energy and kresolved distribution of the orbital character of the band structure reveals that mca largely arises from the spinorbit coupling soc between dx2y2 andd xz,yz orbitals of fe atoms at the ferhmgo interface. Mehta 2 1 school of physical sciences, jawaharlal nehru university, new delhi 110067, india. Highfield cantilever magnetometry as a tool for the. This is known as the magnetocrystalline anisotropy energy 1. It is basically the orbital motion of the electrons which couples with crystal electric field giving rise to the first order contribution to magnetocrystalline anisotropy. Puente orench2,3 1charles university, faculty of mathematics and physics, department of condensed matter physics, ke karlovu 5, cz121 16 prague 2, czech republic.
Therefore, it is not surprising that the internal press consequent upon lattice mismatch between film and. Fe2o3 is investigated by density functional calculations. Ab initio magnetocrystalline anisotropy calculations for. The crystal electric field cef combined with strong spinorbit coupling causes the anisotropy as follows.
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