Tunable Perpendicular Magnetoresistive Sensor Driven by Shape and Substrate Induced Magnetic Anisotropy

Abstract

Control of magnetization reversal processes is a key issue for the implementation of magnetic materials in technological applications. The modulation of shape magnetic anisotropy in nanowire structures with a high aspect ratio is an efficient way to tune sharp in-plane magnetic switching. However, control of fast magnetization reversal processes induced by perpendicular magnetic fields is much more challenging. Here, tunable sharp magnetoresistance changes, triggered by out-of-plane magnetic fields, are demonstrated in thin permalloy strips grown on LaAlO 3 single crystal substrates. Micromagnetic simulations are used to evaluate the resistance changes of the strips at different applied field values and directions and correlate them with the magnetic domain distribution. The experimentally observed sharp magnetic switching, tailored by the shape anisotropy of the strips, is properly accounted for by numerical simulations when considering a substrate-induced uniaxial magnetic anisotropy. These results are promising for the design of magnetic sensors and other advanced magnetoresistive devices working with perpendicular magnetic fields by using simple structures.

Microscale Metasurfaces for On‐Chip Magnetic Flux Concentration

“…The modeled material was permalloy (Py) with magnetic saturation M s = 860 kA m −1 , exchange stiffness A ex = 13 pJ m −1 , and negligible magnetocrystalline anisotropy. [ 19,20 ] The discretization cell size were fixed to ≈10 nm in each direction. Even though this cell size exceeds the exchange length λ ≈ 5 nm, which could result in a loss of accuracy concerning the characteristics of the domain walls, it has been confirmed in a device with R o = 2.5 µm that the results remain nearly invariant for smaller cell sizes.…”

“…The modeled material was permalloy (Py) with magnetic saturation M s = 860 kA m −1 , exchange stiffness A ex = 13 pJ m −1 , and negligible magnetocrystalline anisotropy. [19,20] The discretization cell size were fixed to ≈10 nm in each direction.…”