In ferromagnetic nanostructures domain walls as emergent entities separate uniformly magnetized regions. They are describable as quasi particles and can be controlled by magnetic fields or spin-polarized currents. Below critical driving forces domain walls are rigid conserving their spin structure. Like other quasi particles internal excitations influence the domain wall dynamics above a critic...

Hydrodynamically interacting active particles in an external harmonic potential form a self-assembled fluid pump at large enough Péclet numbers. Here, we give a quantitative criterion for the formation of the pump and show that particle orientations align in the self-induced flow field in surprising analogy to ferromagnetic order where the active Péclet number plays the role of inverse temperat...

We report on confined two-dimensional (2D) dipole clusters formed by small ferromagnetic particles floating at the liquid-air interface and confined by nonuniform external magnetic field. The particles self assemble into hexagonally ordered clusters whose lattice constant can be magnetically tuned. We study the area S, the energy E, the chemical potential mu and the lattice constant a, of 2D cl...

Ferrofluids are stable colloidal suspensions of nanosize ferromagnetic particles in either an aqueous or an oil-based solvent1. In the presence of a magnetic field gradient within a ferrofluid, magnetic forces and torque are developed to drive magnetic particles, which subsequently draw along the liquid solvent carrier. This allows continuous actuation and precise positioning of the ferrofluid ...

Magnetic nanofiber has been widely applied in biomedical fields due to its distinctive size, morphology, and properties. We proposed a novel needleless electrospinning method to prepare magnetic nanofibers from the self-assembling "Taylor cones" of poly(vinyl pyrrolidone) (PVP)/Fe₃O₄ ferrofluid (PFF) under the coincident magnetic and electric fields. The results demonstrated that a static PFF R...

A crucial remaining challenge in the development of the magnetic resonance force microscope (MRFM) is to place the magnetic probe on the mechanical resonator. Here we address the problem of spurious detector response arising from interactions between the magnetic tip and various external applied elds. Ferromagnetic resonance experiments on a microscopic, thin-lm yttrium iron garnet crystal moun...