Dependence of the magneto-optical signal on the Co layer thickness asymmetry in Co/Pt/Co films

Polar unsaturated ferromagnetic thin films are promising for low-power and high-speed nonvolatile resistive and optical memories. Here we measure the magnetooptical (MO) response of polar unsaturated Co90Fe10 and Co40Fe40B20 thin films in the spectral range from 400 nm to 1000 nm using vector magnetooptical generalized ellipsometry (VMOGE) in an out-of-plane applied magnetic field of ±0.4 T where magnetization of the ferromagnetic (FM) thin film is not saturated. Using Magneto- Optical Simulation software (MagOpS®), we extract the complex MO coupling constant ( Q ) of the polar unsaturated FM thin films from difference spectra of VMOGE data recorded in polar configuration at Hz = +0.4 T and at Hz = −0.4 T. Presented approach opens a path to determine Q of both polar saturated and polar unsaturated FM thin films for simulating the MO properties of application-relevant optical memory multilayer structures.

Section: Magnetooptical Analysis Of Multilayer Samplesmentioning

confidence: 99%

A versatile method for exploring the magnetooptical properties of polar saturated and unsaturated ferromagnetic metallic thin films

Patra,

Sharma,

Stöcker

et al. 2024

“…Due to its very precise quantitative results, the GME method has been applied recently to investigate the effects of MO anisotropy [112], the impact of Quantum well states [113], and especially the magnetism of buried interface layers, which produce only rather small changes in MO signal levels but can nonetheless be very robustly detected [114]. Hereby, it is especially the GME enabled access to the full complex nature of the reflection matrix elements, which turns out to be of crucial importance [114].…”

Section: Statusmentioning

confidence: 99%

The 2022 magneto-optics roadmap

Kimel¹,

Zvezdin

Sharma

et al. 2022

Self Cite

“…MO measurement techniques are very important for quantitative materials characterization in ferromagnets [26] and more complex magnetic order states [26][27][28] and moreover, MObased techniques are broadly used by the applied physics community, which stresses their general importance. Specifically, MO Kerr Effect (MOKE) based techniques seem promising here since they have the demonstrated ability to achieve 3-dimensional vector magnetometry [29], exhibit excellent sensitivity to detect magnetism even in single atomic layers [30], and given the fact that previous studies indicated that MOKE techniques are capable to achieve the above even layer resolved for multilayer samples [22,31]. Hereby, the MOKE technique known as Generalized Magneto-optical Ellipsometry (GME) [29,32] is the most promising candidate, given that it detects the complete information that can be measured in a light reflection experiment.…”

Section: Introductionmentioning

confidence: 99%

Magneto-optical detection of non-collinear magnetization states in ferromagnetic multilayers

Martín Valderrama,

Prieto,

Quintana

et al. 2024

We have experimentally studied the relationship in between non-collinear magnetization states in ferromagnetic (FM) multilayers and their resulting magneto-optical (MO) properties. Hereby, we observe that the phase of the complex-valued MO parameters are especially sensitive towards non-collinear magnetization states and enable their unambiguous detection. For the purpose of our experimental study, we designed, fabricated and characterized a set of epitaxial FM/NM/FM multilayers with in-plane uniaxial anisotropy, in which the non-magnetic (NM) interlayer thickness t was varied, so that tunable FM interlayer exchange coupling strength in between the two FM layers could be achieved. Furthermore, the two FM layers were made from different alloys, so that they exhibit different levels of magnetocrystalline anisotropy, which enables a collinear to non-collinear magnetization state transition upon applying a magnetic field H away from the in-plane easy axis for samples with sufficiently large t. Utilizing generalized magneto-optical ellipsometry, we determined the full reflection matrix R as a function of H and we observed that the phases of the complex-valued MO coefficients in R change with H in multilayers that have sufficiently weak interlayer coupling strength, i.e. large t, which can only happen if non-collinear magnetization states of varying non-collinearity occur in those samples. For samples with small t, corresponding to strongly exchange coupled FM layers, this effect is absent, consistent with the existence of collinear magnetization states in those multilayers for all H values.