Paramagnetism and diamagnetism are two distinct types of magnetic properties exhibited by the different elements in nature. Here, we shall learn more about each of them, and find out how they differ from one another.
The Radboud University Nijmegen, the Netherlands, conducted experiments where water and other substances were successfully levitated using the property of diamagnetism. Most spectacularly, a live frog having a large percentage of water―which is a diamagnet―in its body, was levitated.
If you thought that magnetism was simply the process of like poles repelling and unlike poles attracting each other, think again! There are materials out there that will get repelled by both the poles of a magnet, while others that will be attracted by both poles. So how does this happen?
Well, in order to find that out, you will need to understand two important types of magnetism, namely, paramagnetism and diamagnetism. These are the properties which impart attractive and repulsive characteristics to the different materials in nature. In the following sections, we shall tell you what these are, and how they work. We shall also be looking at the main differences between paramagnetic and diamagnetic elements.
Paramagnetism is a form of magnetism displayed by certain selected materials in nature, which causes them to be attracted to an externally applied strong magnetic field. This field causes the creation of induced magnetic fields in paramagnetic materials in the same direction as its own, causing them to be attracted to it.
Paramagnetism results due to the presence of unpaired electrons in the atoms and ions of certain materials. Every element in nature has a different number of electrons, which decides its chemical characteristics. Depending on how these electrons occupy the different energy levels around the nucleus of the element’s atom, some of the electrons tend to remain unpaired. These unpaired electrons don’t have partner electrons having opposite spins to cancel out their spins, and therefore their magnetic properties. As such, they act as micro magnets.
Thus, even in the absence of an external magnetic field, paramagnetic materials have permanent dipole magnetic moments within them. However, its effect is very weak and not significant, as these dipoles tend to orient themselves randomly due to the thermal motion. The result is a net zero dipole magnetic moment in the paramagnetic material, at normal conditions.
When an external magnetic field is applied to a paramagnetic material, the dipoles within it align in the direction of this field. The magnetic effect of each one of them adds up, resulting in a net dipole magnetic moment to be established in the paramagnetic material as a whole, causing it to be attracted to the external magnetic field.
It must be noted that paramagnetism is directly proportional to the strength of the external magnetic field. If the external field is weak, only a small fraction of the spins will be oriented, and so, the resulting induced magnetism will be weak. On the other hand, a strong external field will cause a greater number of spins to be oriented, and hence, the induced magnetism too shall be proportionally larger. Also, when the external magnetic field is removed, the paramagnetic material will lose its magnetic properties completely, and act as a non-magnetic material.
Typically, the materials that have a greater number of unpaired electrons in their atoms show a higher degree of paramagnetism with the creation of a strong magnetic field. These include transition and inner-transition metals.
Diamagnetism is exactly opposite to paramagnetism. It refers to the property of different materials which causes them to get repelled by a strong magnetic field. The diamagnetic materials have a magnetic field induced in them in the opposite direction to the external magnetic field. This has a repulsive effect on them.
Diamagnetism is seen in atoms, ions, and molecules, wherein all the electrons are paired. This means that every electron in an energy level has a partner electron paired with it, having opposite spin. Thus, the net effect of the spins, and therefore magnetic moment, is zero.
When a diamagnetic material is brought within the range of an external magnetic field, the orbital motions of the electrons are disturbed by it, causing a small magnetic moment to be induced in the opposite direction of the external field. This causes the diamagnetic material as a whole to be repelled. When placed between the poles of a strong electromagnet, a diamagnetic material is attracted towards the region having a weak magnetic field.
Diamagnetism occurs in all materials; however, due to its weak nature, it is only observable in materials that do not display other forms of magnetism.
Paramagnetic vs. Diamagnetic Materials: Comparison
● Materials that are attracted by a strong magnet are known as paramagnetic materials. Materials that are repelled by a strong magnet are known as diamagnetic materials.
● Paramagnetic materials have at least one unpaired electron in their atoms. Diamagnetic materials have paired electrons in their atoms.
● The magnetic field that gets created in a paramagnetic material is in the same direction as that of the external magnetic field. The magnetic field that is created in a diamagnetic material is in the opposite direction to that of the external magnetic field.
● Paramagnetism is a stronger magnetic property shown by only a selected number of materials. Diamagnetism is weak property displayed by all materials, and gets easily suppressed and overshadowed in the presence of the stronger magnetic properties.
The following is a list of some important diamagnetic and paramagnetic elements found in nature.
Thus, paramagnetism and diamagnetism are two different magnetic properties that are seen in the different materials around us. Understanding how they work is important for understanding the electromagnetic interactions between the different elements in nature.