What are Non-Magnetic Metals?
Metals that exhibit weak magnetic responses are categorized as non-magnetic metals. In addition, these metals exhibit a low relative permeability.
The measure of magnetization is termed permeability. It is a property that explains the material’s response to the magnetic field.
Magnetism is of three types: Ferromagnetic, Paramagnetic, and Diamagnetic.
Paramagnetic and diamagnetic metals are categorized as non-magnetic metals for their weak magnetic nature.
Type of Metal Nature Magnetic Behavior
Diamagnetic Non-magnetic Weak repulsive magnetic field is induced
Paramagnetic Non-magnetic Weak attractive magnetic field is induced
Ferromagnetic Magnetic Strong attractive magnetic field is induced
What are Non-Magnetic Metals
Classification of metals
Diamagnetic Metals
When placed in an external field, the diamagnetic metals have an induced magnetic field of relatively low magnitude.
This induced magnetic field is repulsive in nature as the electron’s spin is opposite to the direction of the external field.
Therefore, diamagnetic metals can be characterized by their repulsive behavior, whereas paramagnetic and ferromagnetic metals are attracted toward the field.
Paramagnetic Metals
When placed in an external field, the paramagnetic metals experience a weak induced magnetic field, and the electron’s spin is found to be in the direction of the external field.
As a result, these metals are attracted toward the source of the magnetic field.
Ferromagnetic Metals
When placed in an external field, the ferromagnetic metals experience a very strong induced magnetic field, and the electron’s spin is in the direction of the external field.
This inducted field is maintained even at normal temperatures. The demagnetization often involves heating them above the Curie temperature.
Compounds made of multiple elements are termed ferrimagnetic and anti-ferromagnetic.
Ferrimagnetic and anti-ferromagnetic metals have their electron spin opposite to the external magnetic field but vary in the amount of induced magnetic field.
In practice, due to crystal defects, the induced magnetic field in anti-ferromagnetic metals does not exactly oppose the external field. Thus, these materials display certain magnetic responses.
Types of Magnetization
The magnetization of a metal can be classified as natural or man-made.
Natural Magnets
The relative motion of electrons in an atom determines whether the material has magnetic properties or not.
Based on the electron spin, the magnetic property is imparted at the atomic level and transmitted to the crystalline level.
It is at the crystalline level that many magnetic or non-magnetic metals are classified. For example, iron exists in both body-centered and face-centered cubic structures.
The body-centered structure of iron is generally found at room temperature, inducing a ferromagnetic property to the metal.
In contrast, it becomes face-centered and paramagnetic at higher temperatures (above Curie temperature), losing its magnetic properties.
Silver, gold, and platinum are face-centered crystal structures with weak magnetic properties.
Whereas, metals such as iron, cobalt, nickel, and certain rare earth metals are naturally ferromagnetic at room temperature, and are thus classified as natural magnetic metals.
However, the properties of these metals can be altered during manufacturing or heat treatment processes, depending on the temperature.
Generally, permanent magnets are termed metals that can hold magnetic properties for long durations.
Electromagnets
Current and magnetic fields are interconnected. Current can induce a magnetic field in the metal, and the same is the other way around.
When current is passed through a wire-wound iron core, a magnetic field is generated around the coil, thus magnetizing the core.
Thus the magnetized core is called an electromagnet.
Electromagnets use current to magnetize. Once the current is off, it loses its magnetic power. But, by varying the amount of current supplied, varying amounts of magnetization can be developed.
By reversing the direction of the current flow, the position of the poles can be reversed.
A few examples of electromagnets are earphones, loudspeakers, electronic doorbells, etc.
Forced Magnetism
The traditional DIY technique of inducing forced magnetism involves either rubbing weakly magnetic metals against a strong magnet or hitting the metal with a hammer.
These tricks work because the electrons get redistributed in the metal to temporarily create a magnetic moment. But, these effects are temporary and do not last long.
Creating a magnetic metal the DIY way for commercial applications is not useful. Scientists worldwide are trying new techniques to create a longer-lasting magnet.
There are techniques ranging from using additives to using polarized light to alter the material properties. All this involves altering the behavior of electrons in the metals.
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