Magnetism and d Orbitals
What exactly gives rise to magnetism?
We see generally megnitism in transition metals and their compounds,
manganese, iron, cobult, cadmium. Why do specifically d orbital atoms
give rise to magnetism?
Since magnetism is caused, in part, due to spin (clearly other
considerations such as spin-orbit coupling). d states have 5 potential
orbitals with can each "hold" 2 electron states each. Electron states occupy
orbitals with a spin up or down configuration. Hence partially occupied
states, give a net spin up or down. This is explanation is very much
simplified. Similar arguments hold for other transition series, such as the
lanthanides and actinides.
A magnetic field results from moving electric charge. The strongest magnets
results from electric charge moving in a circle. If you examine the
structure of an electro-magnet, you will see a large number of wires looped
in alligned circles.
Every atom has charged electrons spinning around the nucleus. Each orbiting
electron produces its own magnetic field. Each atom produces a small
magnetic field. In materials such as iron, the atoms can allign their
magnetic fields quite easily. This produces a strong magnetic field.
Crystal structures do not allow easy reorientation of the atoms, so magnetic
allignment is not easy to achieve. In liquids and gases, the atoms are too
free to move. They cannot hold the allignment.
Magnetism is caused by the presence of electrons with unpaired spin. The
unpairing is temporary [or induced] or permanent depending upon the atom or
ion. Lutetium with 15 unpaired electrons is the monarch of naturally
occurring magnetic elements.
Click here to return to the Physics Archives
Update: June 2012