Focused Ion Beam patterning of MnSb(1-101) based spintronic devcies

TL;DR

This study demonstrates how focused ion beam patterning affects the magnetic and electronic transport properties of MnSb devices, revealing disorder-induced changes in Hall effects and resistivity, relevant for spintronic applications.

Contribution

It introduces a method to pattern MnSb spintronic devices with FIB and quantifies the disorder effects on their transport properties, highlighting potential for future device development.

Findings

FIB patterning modifies the anomalous Hall effect and resistivity in MnSb.

Disorder from Ga ion dose reduces the Hall conductivity to zero beyond a threshold.

Magnetic and transport behaviors are sensitive to FIB-induced damage and uniformity.

Abstract

Low temperature transport measurements are presented of ferromagnetic MnSb devices with the magnetic properties patterned using a Ga focused ion beam FIB system at 30 keV. FIB patterning introduces disorder and this is quantified in this paper through measurements of the longitudinal resistivity and the anomalous Hall effect contribution to the Hall conductivity. The MnSb structural phase is the niccolite phase with a surface state in addition to bulk states. FIB doses up to 1E16 Ga ions per square cm reduces the anisotropic magnetoresistance signal but increases the size of the anomalous Hall effect signal in out of plane magnetic fields, B. The anomalous Hall effect contribution to the Hall conductivity is e squared divided by h in the undamaged devices, where e is the electronic charge and h is Plancks constant. This quantity is sensitive to the level of disorder induced by the Ga ion beam, reducing to zero at dose levels greater than 1E16 Ga ions per square cm. The resistivity shows a logarithmic B dependence after the magnetization has saturated with the low field anisotropic magnetoresistance contribution of 0.12 percent. The conductivity change is e squared divided by h in the magnetic field range of logarithmic B behavior. The resistivity shows a reduced fit to a logarithmic B dependence at high FIB dose levels and is dependent on the damage uniformity. Patterning nanostructured magnetic behavior in MnSb, with compatibility to altermagnetic materials, in particular the niccolite phase of CrSb and non trivial Berry phase contributions to transport make this ferromagnetic material and patterning technique useful for future spintronic device development.