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Ferromagnetism is a scientific phenomena in which certain electrically uncharged materials attract others strongly. Lodestone (or magnetite, an oxide of iron, Fe3O4) and iron, both occurring in nature, have the capacity to develop such appealing properties and are commonly referred to as natural ferromagnets. They were discovered about 2,000 years ago, and all early scientific investigations of magnetism were carried out on these materials. Today, ferromagnetic materials are employed in a wide range of daily products, such as electric motors and generators, transformers, telephones, and loudspeakers.
What is Ferromagnetism?
Ferromagnetism is a scientific phenomena in which certain electrically uncharged materials attract others strongly. It is a kind of magnetism related to iron, cobalt, nickel, and various alloys or compounds containing one or more of these metals. Gadolinium and a few other rare-earth elements contain it as well. Unlike other substances, ferromagnetic materials are easily magnetised, and under intense magnetic fields, magnetization approaches a fixed limit known as saturation. The magnetization does not restore to its previous value when a field is applied and subsequently withdrawn. After being treated to such an external magnetic field, ferromagnets will tend to remain magnetised to some extent. This proclivity to “remember their magnetic past” is known as hysteresis.
What is Hysteresis?
If you pay great attention to your air conditioner (set to, say, 78 degrees), you may observe that it turns on when the temperature climbs to 79 degrees and goes off when the temperature lowers to 77 degrees. This is known as hysteresis, and AC units are purposefully constructed in this manner. If the unit cycled at 78 degrees in both directions, it would turn on and off far more frequently, causing it to wear out faster.
The temperature at which the unit flips depends on the direction the temperature is travelling due to hysteresis.
A physical system exhibits hysteresis when its output is dependent on both current and past inputs. The behaviour of the AC unit at the set point (78 degrees in our example) is determined by recent temperature history: if the temperature rises through 78 degrees, the system will be off until the temperature reaches 79 degrees; if the temperature falls through 78 degrees, the system will be on until the temperature reaches 77 degrees. The direction of temperature change is important, and determining that direction necessitates information not just of the current temperature but also of temperatures in the recent past.
What is Curie temperature?
For a ferromagnetic material, the Curie temperature is critical. For example, if a ferromagnetic material is heated below its Curie temperature, the substance experiences net spontaneous magnetization, which implies it becomes ferromagnetic, or magnetic. If a ferromagnetic substance is heated above its Curie temperature, it becomes paramagnetic, or does not become a magnet.
Iron has a Curie temperature of 1043 K. Even sources from before 1984 have the Curie temperature of iron at the same number as more recent sources. When the temperature of iron is at or above the Curie temperature, it becomes paramagnetic; when the temperature of iron is below the Curie temperature, it becomes ferromagnetic. Every element has a different Curie temperature. Iron, for example, has a different Curie temperature than Cobalt or Nickel.
Causes of Ferromagnetism
Atomic dipoles in small portions of an unmagnetized ferromagnetic material known as domains are all orientated in the same direction. The domains have a net magnetic moment even in the absence of an external magnetising force. In contrast, the magnetic moments of neighbouring domains are pointing in opposite directions. They cancel each other out, resulting in a net magnetic moment of zero for the substance. When an external magnetic field is introduced, all of these domains align in the field’s direction. As a result of this process, the material becomes strongly magnetised in a direction parallel to the magnetising field.
Use of Ferromagnetic Material
Ferromagnetic materials are often utilized for nonvolatile data storage in cassettes, hard drives, and other devices. They have two primary technical applications: I as flux multipliers that constitute the nucleus of electromagnetic machines, and (ii) as energy (magnets) or information storage (magnetic recording). Because of the interplay of electric current and light with magnetic order, they are also employed for information processing. Ferromagnetic materials include iron, nickel, and cobalt.
Examples of Ferromagnetic material
Metals make up the vast bulk of ferromagnetic materials. Common examples include iron, cobalt, nickel, and other ferromagnetic metals. Metallic alloys and rare earth magnets are also ferromagnetic materials. Magnetite is a ferromagnetic substance created by the oxidation of iron. Curie temperature is 580 degrees Celsius. It has previously been identified as a magnetic material. Magnetite is the most magnetic natural mineral in the world.
Conclusion
It is a kind of magnetism related to iron, cobalt, nickel, and various alloys or compounds containing one or more of these metals. The temperature at which the unit flips depends on the direction the temperature is travelling due to hysteresis. The direction of temperature change is important, and determining that direction necessitates information not just of the current temperature but also of temperatures in the recent past. For a ferromagnetic material, the Curie temperature is critical. For example, if a ferromagnetic material is heated below its Curie temperature, the substance experiences net spontaneous magnetization, which implies it becomes ferromagnetic, or magnetic. When the temperature of iron is at or above the Curie temperature, it becomes paramagnetic; when the temperature of iron is below the Curie temperature, it becomes ferromagnetic.
