Scaling of quadratic and linear magneto-optic Kerr effect spectra with L21 ordering of Co2MnSi Heusler compound

Abstract

The Heusler compound Co 2 MnSi provides a crystallographic transition from B2 to L2 1 structure with increasing annealing temperature T a , being a model system for investigating the influence of crystallographic ordering on structural, magnetic, optic, and magnetooptic (MO) properties. Here, we present quadratic magnetooptic Kerr effect (QMOKE) spectra depending on M 2 in addition to the linear magnetooptic Kerr effect (LinMOKE) spectra being proportional to M , both in the extended visible spectral range of light from 0.8 eV to 5.5 eV. We investigated a set of Co 2 MnSi thin films deposited on MgO(001) substrates and annealed from 300 • C to 500 • C. The amplitude of LinMOKE and QMOKE spectra scales linearly with T a , and this effect is well pronounced at the resonant peaks below 2.0 eV of the QMOKE spectra. Furthermore, the spectra of the MO parameters, which fully describe the MO response of Co 2 MnSi up to the second order in M , are obtained dependend on T a . Finally, the spectra are compared to ab-initio calculations of a purely L2 1 ordered Co 2 MnSi Heusler compound.

Structural and Magnetic Properties of Inverse-Heusler Mn2FeSi Alloy Powder Prepared by Ball Milling

“…The current rapid development of technology increases the requirements for materials research and the search for new material compositions. One of the attractive and currently investigated classes are Heusler alloys, which contain more than 4000 potential members and are applied in the fields like spintronics [1], magnetooptics [2,3], magnetoresistance and magnetocaloric devices [4,5], topological materials [6], shape memory alloys [7,8], spin injectors [9], etc. In general, regular types of Heusler materials are ternary intermetallic compounds with composition of elements X 2 YZ (full-Heusler) or XYZ (half-Heusler), where X and Y are transition metals (e.g., Fe, Co, Mn) and Z is an s, p element, e.g., Si, Al, In, Sn.…”

The 2022 magneto-optics roadmap

“…The MOKE spectroscopy can be established as a standard tool to quickly and cheaply characterize crystal quality of prepared FM films, having advantage of implicit sensitivity to FM material. The sensitivity to structural details of FM layer can be further enhanced by employing also QMOKE spectroscopy, as demonstrated in the case of Co 2 MnSi [53] (figure 4). However, MOKE spectroscopy is currently not established as a routine tool to check crystal quality of FM layer.…”

“…Determination of their spectra extends usual linear spectral magnetooptics (see section 4). The spectra of G s and 2G 44 were determined for bcc Fe [51,52] and Heusler compound Co 2 MnSi [53] (figure 4). In both cases, the G-spectra were about 10× smaller compared to their linear-in-magnetization counterparts.…”

Cubic magneto-optic Kerr effect in Ni(111) thin films with and without twinning

“…In addition, quadratic-in-magnetization MOKE (QMOKE) [12,13], being magnetic linear dichroism and birefringence upon reflection proportional to M 2 , can be employed to study antiferromagnets, for example in time-resolved experiments [14][15][16]. QMOKE showed to be sensitive to the structural ordering of Heusler compounds [17,18] and to spin-orbit torque effects [19]. Vectorial magnetometry including QMOKE [20][21][22][23][24], QMOKE spectroscopy [18,[25][26][27][28], as well as QMOKE microscopy [29,30] have been realized.…”

“…QMOKE showed to be sensitive to the structural ordering of Heusler compounds [17,18] and to spin-orbit torque effects [19]. Vectorial magnetometry including QMOKE [20][21][22][23][24], QMOKE spectroscopy [18,[25][26][27][28], as well as QMOKE microscopy [29,30] have been realized. However, any higher-order MOKE, such as cubic-inmagnetization MOKE (CMOKE), being proportional to M 3 , has only been mentioned very rarely so far [31][32][33] and has not yet been systematically investigated.…”