Controlling Chiral Spin Texture in RE:TM Ferrimagnetic Alloys Thin-Films by Engineering the Vertical Compositional Distribution

Controlling chiral spin texture has garnered significant research attention in spintronics. Recent study suggests the Dzyaloshinskii-Moriya Interaction (DMI) can be manipulated to stabilize chirality by introducing non-uniformity via compositionally-grading in amorphous rare earth (RE): transitional metal (TM) ferrimagnetic thin films. These alloys exhibit magnetization compensation points, where the net magnetization or angular momentum vanishes due to competition between opposing RE and TM moments. Near compensation a substantial increase in spin-orbit torque (SOT) efficiency and the occurrence of perpendicular magnetic anisotropy (PMA) have been observed. PMA is observed only within a certain composition range and a compositional gradient enables a transition from in-plane to out-of-plane magnetization, yielding an exchanged couple configuration of magnetic moments and also a chiral spin texture within the layer. A key aim of this experiment is to use the unique capabilities of PNR in both the non-spin-flip (NSF) and spin-flip (SF) modes for magnetic and structural depth profiling to effectively map the spatial distribution of magnetization through the thickness of designed-in Gd alloy gradients to map the chiral spin texture. This will complement and complete our recent studies of RE:TM graded alloy using resonant x-ray studies from the ESRF.