Magnetic switching modes for exchange spring systems with competing anisotropies

Abstract

Hard-soft multilayer a b s t r a c tThe magnetization reversal processes of ½10 nm ErFe 2 =nYFe 2 =4 nm DyFe 2 =nYFe 2 multilayer films with a (11 0) growth axis and a variable YFe 2 layer thickness n are investigated. The magnetically soft YFe 2 compound acts as a separator between the hard rare earth (RE) ErFe 2 and DyFe 2 compounds, each of them bearing different temperature dependent magnetic anisotropy properties. Magnetic measurements of a system with n ¼ 20 nm reveal the existence of three switching modes: an independent switching mode at low temperatures, an ErFe 2 spin flop switching mode at medium high temperatures, and an YFe 2 dominated switching mode at high temperatures. The measurements are in qualitative agreement with the findings of micromagnetic simulations which are used to illustrate the switching modes. Further simulations for a varied YFe 2 layer thickness n ranging from 2 to 40 nm are carried out. Quantitative criteria are defined to classify the reversal behavior, and the resultant switching modes are laid out in a map with regard to n and the temperature T. A new coupled switching mode emerges above a threshold temperature for samples with thin YFe 2 separation layers as a consequence of the exchange coupling between the magnetically hard ErFe 2 and DyFe 2 layers. It reflects the increasing competition of the two conflicting anisotropies to dominate the magnetic switching states of both RE compounds under decreasing n.

Impedance spectroscopy analysis of 0.7BiFeO3-0.3BaTiO3/BiY2Fe5O12 composites with simultaneously improved magnetization and remnant polarization

“…This phenomenon is due to the fact that the BYIG is a classical soft magnetic ferrite [13]. One can also find the kinks of the M-H loops due to the higher coercivity of BFO-BT compared with the soft magnetic BYIG phase [14].…”

Exchange-spring driven spin-flop transition in DyFe 2 /YFe 2 superlattices

“…• out-of-plane angle for DyFe 2 at room temperature [18,19], a factor of 2.5 [20] has to be multiplied to the magneto-elastic anisotropy obtained from the single-ion model. In contrast, the previous micromagnetic study [8] of the same system used the as-derived magneto-elastic anisotropy.…”

Micromagnetic simulation of ferrimagnetic TbFeCo films with exchange coupled nanophases

“…FiM materials have been extensively studied in numerical modeling. Various methods, ranging from Monte Carlo to mircomagnetics, have been employed to study the temperature dependence of magnetic properties in FiM [10][11][12]. Magnetic reversal dynamics and EB effects involving FiM have also been investigated numerically [13][14][15][16][17][18][19][20].…”

“…Monte Carlo Metropolis sampling was employed to investigate the EB effect in FM core/FiM shell structure [16]. Using micromagnetic model, EB effects were obtained and compared to experimental results in exchange-coupled FiM/FM heterostructures [17,18], FiM bilayers [19], and multilayers [11,12,20]. In this paper, we present a micromagnetic model to study heterogeneous magnetic materials with two interpenetrating nanoscale phases.…”