Analysis of wasp-waist hysteresis loops

Abstract

Wasp-waist and pot-belly hysteresis loops have been observed in many materials. When only the major loop is reported, the results are insufficient to establish which processes are involved. We present two models for wasp-waist materials that produce virtually indistinguishable major loops, but show that first-order reversal curves can be used to separate the effects. In the simplest model, we take a soft magnetic material and a hard material and exchange couple them. When the exchange is positive, the loop is conventional. However, for negative (antiferromagnetic) exchange, the wasp-waist loop is obtained. Negative coupling of two materials with different switching field distributions leads to pot-bellied loops.

Observation of complete inversion of the hysteresis loop in a bimodal magnetic thin film

“…The area within the hysteresis loop reflects the energy dissipated during the field cycle, and the negative area for the completely inverted loops would violate the first law of thermodynamics-a discrepancy that initially was explained through the so-called inhomogeneity effect [2,15,16]. Simultaneously theoretical models, such as wasp-waist hysteresis loops, the Preisach model of hysteresis, etc., were proposed [14,[17][18][19]. Furthermore it was argued that inverted loops could arise from experimental artifacts rather than inhomogeneity [20].…”

High-pressure synthesis, structural and complex magnetic properties of the ordered double perovskite Pb2NiReO6

“…It is also interesting to note, that the saturation moment value (0.39 µB) is close to that observed for the Pb 2 NiReO 6 -LT sample. The origin of the striking feature observed in the wasp-waisted hysteresis loops results from a mixture of magnetic components with contrasting coercivities 33 , i. e. FM and AFM components. Such a mixture will result in a bias of the magnetic parame- ters towards one or another constituent, producing distinctive wasp-waisted shapes; the degree of wasp-waistedness will be dependent on the relative contribution of each component 33 .…”

Методы управления спиновой инжекцией в спиновых светоизлучающих диодах InGaAs/GaAs/Al-=SUB=-2-=/SUB=-O-=SUB=-3-=/SUB=-/CoPt

“…Наличие магнитной структуры, содержащей области " магнито-мягкой" и " магнитожесткой" фаз хорошо согласуется с моделью обменного взаимодействия двухфазных ферро-магнитных систем, рассмотренной в [16]. Согласно [16], взаимодействие фаз проявляется в наличии особенно-стей на петле гистерезиса магнитополевой зависимости намагниченности (а именно, сужение петли в окрест-ности нулевой намагниченности). Подобные особенно-сти зарегистрированы на магнитополевых зависимостях намагниченности исследованных слоев CoPt [6].…”