A High-Resolution Combined Scanning Laser- and Widefield Polarizing Microscope for Imaging at Temperatures from 4 K to 300 K

Abstract

Polarized light microscopy, as a contrast-enhancing technique for optically anisotropic materials, is a method well suited for the investigation of a wide variety of effects in solid-state physics, as for example birefringence in crystals or the magneto-optical Kerr effect (MOKE). We present a microscopy setup that combines a widefield microscope and a confocal scanning laser microscope with polarization-sensitive detectors. By using a high numerical aperture objective, a spatial resolution of about 240 nm at a wavelength of 405 nm is achieved. The sample is mounted on a ${}^4$He continuous flow cryostat providing a temperature range between 4 K and 300 K, and electromagnets are used to apply magnetic fields of up to 800 mT with variable in-plane orientation and 20 mT with out-of-plane orientation. Typical applications of the polarizing microscope are the imaging of the in-plane and out-of-plane magnetization via the longitudinal and polar MOKE, imaging of magnetic flux structures in superconductors covered with a magneto-optical indicator film via Faraday effect or imaging of structural features, such as twin-walls in tetragonal SrTiO${}_3$. The scanning laser microscope furthermore offers the possibility to gain local information on electric transport properties of a sample by detecting the beam-induced voltage change across a current-biased sample. This combination of magnetic, structural and electric imaging capabilities makes the microscope a viable tool for research in the fields of oxide electronics, spintronics, magnetism and superconductivity.

arXiv comment14 pages, 11 figures. The following article has been accepted by Review of Scientific Instruments. After it is published, it will be found at http://aip.scitation.org/journal/rsi

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Cited by in corpus (5)

• Quantitative magneto-optical investigation of superconductor/ferromagnet hybrid structures
• Catastrophic magnetic flux avalanches in NbTiN superconducting resonators
• Enhancing magneto-optic effects in two-dimensional magnets by thin-film interference
• Magneto Optical Sensing beyond the Shot Noise Limit
• Optical imaging of strain-mediated phase coexistence during electrothermal switching in a Mott insulator