Higher-order magnetooptic Kerr effect in magnetic thin films

Date

May 6, 2026

Time

2:00 PM - 3:00 PM

Speaker

PD Dr. Timo Kuschel

Affiliation

Institute of Physics, Johannes Gutenberg University Mainz

Language

en

Main Topic

Materialien

Host

Ines Firlle

Description

The magneto-optic Kerr effect (MOKE) describes the change of polarization state apon reflection of polarized light from a magnetized sample [1]. Initially, this effect has been assumed to be proportional to the magnetization M of the investigated sample and, thus, became a standard tool to study magnetic thin-film systems, e.g. via Kerr spectroscopy, time-resolved MOKE, or Kerr imaging [2,3]. However, in the last two decades contributions of second order in M have been explored [4]. The so-called quadratic MOKE (QMOKE) is proportional to M2 and can be utilized, e.g., to study antiferromagnetic materials [5] since the MOKE linear in M vanishes here due to the antiparallel alignment of the magnetic moments. Recently, we have identified MOKE contributions of third order in magnetization (cubic MOKE, CMOKE) being proportional to M3 [6] and studied its dependence on the structural domain twinning of Ni(111) thin films characterized by off-specular x-ray diffraction mappings. In my talk, I will introduce higher-order MOKE effects and discuss recent examples. We have investigated the QMOKE in Fe [7] and Heusler compound thin films [8], and confirmed the linear dependence of the QMOKE on the structural order of the Heusler compound in a wide spectral range. We are able to describe the angular dependencies of QMOKE and CMOKE with respect to the crystal orientation of the thin films. For example, while it is quite simple to find CMOKE in (111)-oriented films, it is not straightforward to identify it in (001)-oriented samples [9]. I will discuss the reasons. Finally, I will show that the CMOKE in Co(111) thin films can reach up to 30% of the linear MOKE signal [10] which is promissing for future research applications such as CMOKE microscopy, spectroscopy and pump probe experiments.

Links

• Seminars at the IFW

Last modified: Apr 30, 2026, 7:35:32 AM