Vous avez cherché: coercivity (Anglais - Arabe)

coercivity
مقاومة مغناطيسية

gnetic information achieved in monodispersity [5], their self-assembly into 2d superlattices [6, 7], and in the accomplished anisotropy energies per constituent atom [8, 9]. despite their promising properties for applications, 3d nanoparticles present several difficulties. although the magnetic properties of a single particle can be addressed [10], it is almost impossible to study the morphology of the particle in conjunction with its magnetism. the particles frequently have a few atomic layers of oxide at their surface, which are not ferromagnetic [11]. this causes uncertainties in the morphology of the ferromagnetically ordered particle core. owing to these difficulties, no general view on the origin of anisotropy in nanoparticles has yet evolved. the anisotropy has either been attributed mainly to the volume [12] or surface [10] contribution of the crystalline lattice, or to shape anisotropy caused by eccentricities of the magnetic core [11]. a second difficulty is the out-of-plane alignment of the easy magnetization axes in colloidal monolayers. an individual particle can have several easy magnetization axes. in addition, the deposited particles are randomly oriented and therefore their axes point into random directions [13]. however, every in-plane component of the magnetization leads to undesired dipolar interactions. attempts of applying out-of-plane magnetic fields during deposition piles up the particles by dipolar interactions and thereby inhibits formation of ordered monolayers [8]. a third difficulty is coalescence between adjacent particles upon annealing. this equally leads to high blocking temperatures and is often difficult to discern from the desired coercivity increase in the individual particles by change of their crystalline structure [12]. 2d nanostructures at surfaces are optimally suited to address the origin of anisotropy, and also to explore density limits of non-interacting magnetic units. the anisotropy imposed by the substrate makes them uniaxial, for example oriented outof- plane. the size and spatial uniformity achieved by self-assembly techniques [14–16] are comparable to those of colloids. under ultrahigh vacuum conditions, there is no oxide shell and all constituent atoms are ferromagnetically ordered. thus, the particle morphology contributing to the magnetic signal is accessible at the atomic scale and can be related to the magnetic properties measured in situ with integrating techniques. inspired by these advantages, and by the technological relevance of the questions, whether on computer hard disks or in mrams (magnetic random access memories), requires elaborate tuning of the preferred (easy) magnetization axis, of the magnetic anisotropy energy (mae), and of the magnetic moment in the units used to store a bit. these units are single domain particles (with diameter do20 nm) where the magnetic moments of all atoms are ferromagnetically aligned [1] to form the overall magnetic moment of th
يتطلب استكشاف حدود الكثافة القصوى لتخزين المعلومات المغناطيسية ، سواء على الأقراص الصلبة للكمبيوتر أو في mrams (ذاكرة الوصول العشوائي المغناطيسية) ، ضبطًا مفصلًا لمحور المغنطة (السهل) المفضل ، وطاقة التباين المغناطيسي (mae) ، والمغناطيسية. لحظة في الوحدات المستخدمة لتخزين قليلا. هذه الوحدات عبارة عن جسيمات مجال واحد (بقطر 20 نانومتر) حيث يتم محاذاة اللحظات المغناطيسية لجميع الذرات مغناطيسيًا [1] لتشكيل العزم المغناطيسي الكلي لل