Carbon tip aperture cantilevers: Fabrication & features in near-field magneto-optical imaging

•Particular way to reveal the nanoscale features of domain structures is considered.•Near field polarization measurements by carbon aperture cantilevers is implemented.•Aperture cantilever fabrication bases on focused ion beam treatment.•Magneto-optical resolution below 100 nm is shown. Improving the ways of magnetic structure investigation with the lowest possible resolution is important in the study and practical implementation of fundamental magnetism. Here we discuss one of the most modern magneto-optical method of domain structure (DS) imaging, scanning near-field magneto-optical microscopy (SNMOM), and propose the new technology based on focused ion beam (FIB) treatment to produce aperture cantilevers with carbon hollow pyramid tip (ACCT). Estimated ACCT light transmission coefficients show better results compare to commonly used aperture silicon cantilevers. By measuring the polarization characteristics of aperture with diameter from 83 to 263 nm, we illustrate the possibility of ACCT to maintain a liner polarization of transmitted light. Testing of ACCT in atomic-force and SNMOM modes shows that ACCT are the effective tool in near-field imaging. Features of morphology and DS of Bi-substituted iron garnet (Bi: IG) films synthesized and used as the test objects, including DS peculiarities of 100 nm-size, is revealed.