Anisotropy manifests itself in dramatic fashion as unexpected physical phenomena of magnetic attraction-repulsion, which is analogous to love-hate relationship. Experiments appear to defy basic law of nature, raising more questions than answers. Such a fundamental discovery could lead to some industrial applications in future.
Homo-Magnetic Like-Pole Attraction
Conventional wisdom dictates that like poles repel and opposite poles attract.
Thus, the S-pole of a small-diameter rod-shaped or disc-shaped permanent magnet attaches to the N-pole of a large-diameter disc-shaped permanent magnet as expected, as shown in Figure 1, albeit only to the peripheral region where the magnetic flux density is the highest.
However, the N-pole of a small-diameter rod-shaped or disc-shaped permanent magnet attaches to the central region of the N-pole of a large-diameter disc-shaped permanent magnet in concentric alignment, as shown in Figure 2, due to temporary magnetic-pole inversion!
It is known that a strong external magnetic field can permanently alter the sizes and orientations of magnetic domains in a permanent magnet. This is not the case here because the central region of the large-diameter disc-shaped permanent magnet has weaker magnetic field (i.e., sparser magnetic field lines) than the peripheral region of the large-diameter disc-shaped permanent magnet does.
The phenomenon is analogous to the N-pole of a small-diameter rod-shaped or disc-shaped permanent magnet attaching to the N-pole of a large-diameter ring-shaped permanent magnet at the middle in concentric configuration with a thin membrane separator in-between.
The like-pole magnetic attraction can be observed between 2 rare-earth magnets of dissimilar sizes, or between 2 AlNiCo magnets of similar sizes.
Figure 1. N-S Attraction
Figure 2. N-N Attraction
Ferromagnetic Boundary Repulsion
Conventional wisdom dictates that a permanent magnet only attracts an unmagnetized object made of ferromagnetic material (Fe, Co, Ni, etc.).
However, a linear unmagnetized object made of ferromagnetic material experiences a repulsive force exactly at the boundary between the 2 polarities of a permanent magnet!
The effect shows up only if the linear unmagnetized object made of ferromagnetic material attempts to touch the permanent magnet in parallel to the N-S boundary. If the linear unmagnetized object made of ferromagnetic material attempts to touch the permanent magnet in perpendicular to the N-S boundary, then an attractive force is exerted as expected.
The repulsive force is best felt by an extended paperclip made of steel as a probe, approaching the N-S boundary of a spherical or hemispherical rare-earth magnet from a distance above pointing towards the centre of the rare-earth magnet, as shown in Figure 3 and Figure 4.
Figure 3. Attraction
Figure 4. Repulsion
Ferromagnetic Penetrative Levitation
Conventional wisdom dictates that a permanent magnet does not repel an unmagnetized object made of ferromagnetic material (Fe, Co, Ni, etc.).
However, a small rod-shaped unmagnetized object (e.g., a cut nail) made of ferromagnetic material placed just above a ring-shaped permanent magnet causes magnetic levitation along the central axis of the ring-shaped permanent magnet due to induced magnetism! The steel nail is not permanently magnetized.
The repulsive force is quite unstable, so the rod-shaped unmagnetized object made of ferromagnetic material must be supported by a tube (e.g., a plastic straw) above the ring-shaped rare-earth magnet, as shown in Figure 5.
Figure 5. Levitation
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