Interplay between collective pinning and artificial defects on domain wall propagation in Co/Pt multilayers

Abstract

Abstract.The interplay between collective pinning on intrinsic structural defects and artificial pinning at a patterned hole is studied in magnetic multilayers with perpendicular anisotropy. The pinning strength of a patterned hole is measured through its efficiency to stop domain wall propagation into a consecutive unpatterned nanowire section (using antisymmetric magnetoresistance to detect the direction of domain wall propagation) whereas collective pinning is characterized by the field dependence of domain wall velocity. Close to room temperature, collective pinning becomes weaker than artificial pinning so that pinning at the hole compensates nucleation-pad geometry, blocking domain wall propagation across the nanowire.

Numerical study of the roughness of domain walls in the 2-dimensional random bond Ising model using a weighed-loop algorithm

“…The dynamics in the creep regime and static properties of domain walls are related through the roughness (or wandering) exponent. In case of domain walls in the 2D random-bond Ising model (RBIM) this exponent is ζ RB = 2/3 [6,7] and is in agreement with experiments on PMA's [4,[8][9][10]. In case of random-field disorder this exponent is ζ RF = 1 [11,12] in contrast to ζ T = 1/2 when thermal fluctuations dominate the behaviour.…”

Crossed-ratchet effects and domain wall geometrical pinning

“…These kind of boundaries can pin the interface by locally reducing its extension, thus saving surface tension energy. For extended domain walls this kind of pinning has been recently realized experimentally and showed to be able to modify the magnetization dynamics 7,16,[18][19][20] and to produce, in particular, inter-esting ratchet transport of magnetic domain walls 3,24 . Being mostly geometrical (i.e.…”

“…7,[19][20][21][22][23] These kind of boundaries can pin the interface by locally reducing its extension, thus saving surface tension energy. For extended DW this kind of pinning has been recently realized experimentally and showed to be able to modify the magnetization dynamics 7,16,[18][19][20] and to produce, in particular, interesting ratchet transport of magnetic DW. 3,24 Being mostly geometrical (i.e., determined mostly by the shape and distribution of holes or by the geometry of the boundaries and not much by the specific microscopic pinning interaction) this kind of pinning has the advantage over other artificial pinning mechanisms that it can be more easily tailored at a wide range of scales to control the wall motion in various specific ways.…”

“…A particularly interesting case of interface pinning is the "geometrical pinning" induced by the presence of artificially introduced holes or antidots [16][17][18] , or by a spatial modulation of the sample boundary conditions in narrow samples 7,[19][20][21][22][23] . These kind of boundaries can pin the interface by locally reducing its extension, thus saving surface tension energy.…”

Switchable field-tuned control of magnetic domain wall pinning along Co microwires by 3D e-beam lithographed structures

“…Moreover, compacting and minimizing actual magnetic circuits to manage storage of data bits in less space is always a matter of active research. Domain wall pinning in magnetic microwires is often tuned using 2D magnetic patterns that include notches [3], holes [4], thickness modulation [5] or nearby nanomagnets [6]. Current trends explore the adequacy of threedimensional magnetic systems, which benefit from this third dimension to add more degrees of freedom to the existing bidimensional devices [1,7].…”