Figure 2. Magnetic orientation and dynamics of paramagnetic hemozoin crystals with anisotropic easy-plane character.

In these schematic drawings, the cylinders represent the suspended hemozoin crystals. The axes of the cylinders correspond to the magnetic hard axes of the crystals and not related to their fore-axes. (a) Without external magnetic field the crystals in the suspension are randomly oriented. (b) With the application of a magnetic field, the hard axes of the crystals begin to align perpendicular to the magnetic field vector B, though this orientation is hindered by the thermal fluctuations. (c) In the high-field limit this two-dimensional alignment is completed, with the hard axis of each crystal lying within the plane normal to the field. (d) In slowly rotating fields the crystallites behave as magnetically driven micro-rotors. (e) Due to the viscosity of the fluid, at high rotation frequencies their hard axes tend to align parallel to the rotation axis and consequently they stop spinning. Only in this case a full three dimensional alignment of the hard axes is achieved.