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Significant breakthroughs in the theory and applications of ferrofluid have broadened their usage in areas such as sealing and actuation. However, the development of numerical ferrofluid dynamics has been slow owing to inadequate multi-field coupling techniques and incomplete equations for turbulence in ferrofluid flow. The understanding of low-Reynolds-number turbulent flow mechanisms in ferrofluid at small scales, particularly in sealing and actuation applications, remains limited, therefore hindering further advancements. This article delves into the turbulent flow equations for general fluid and discusses the influence of different-scale vortices on the average fluid motion. An anisotropic turbulence model was introduced and verified using fluid flow around a cylinder. Magnetic and flow fields data were coupled through node ranking and interpolation methods. By introducing the interaction force of magnetic dipoles, the turbulent equations were refined within Euler grids, thereby establishing a numerical model for the turbulent motion of ferrofluids influenced by multiple fields. This model was applied to study the deformation and migration processes of ferrofluid under an external magnetic field. The variations in ferrofluid motion under magnetic forces were encapsulated, and macroscopic flow comparisons were made through experiments, which demonstrated good consistency. This research provides new methods and ideas for use in ferrofluid numerical studies. Additionally, it offers valuable technical support that can aid in developing industrial products such as sealing and driving devices based on ferrofluids. [ABSTRACT FROM AUTHOR]

Ultrathin ferromagnetic films display a wealth of spectacular characteristics, one of which is that two-dimensional ferromagnetism is stabilized exclusively by magnetic anisotropies. In this work, we experimentally demonstrated the realization of ultrathin yttrium iron garnet (Y3Fe5O12) films with perpendicular magnetic anisotropy by pulsed laser deposition. A labyrinthine magnetic domain configuration in Y3Fe5O12 was identified by magnetic force microscopy, qualitatively determining that the magnetic moment possesses an out-of-plane component. Magnetic moments in the Y3Fe5O12 film were investigated by using a vibrating sample magnetometer and magnetic circular dichroism spectroscopy. Due to the surface sensitivity, the characterization technique based on magnetic circular dichroism spectroscopy presents as a high-resolution magneto-optical method to determine the magnetic property quantitatively, which has an advantage over the vibrating sample magnetometer technique commonly used for bulk crystals or powders, especially when the paramagnetic background from the supporting substrate is non-negligible. Our work introduces the burgeoning material synthesis and processing technology, and miscellaneous characterization techniques into the study of conventional magnetic oxide films, providing powerful supplements to the detection and modulation of magnetism at the nanoscale. [ABSTRACT FROM AUTHOR]