The History of Magnets - A Look into the History of Magnetism

The long history of magnets and the discovery of magnetism began with the first discovery of lodestones. It is impossible to name a true inventor of magnets, as naturally occurring materials such as lodestones with magnetic properties exist but were discovered rather than invented. The name "magnet" likely derives from early sites in the Magnesia region of Greece. The discovery of magnets is often attributed to Thales of Milet. According to legend, the Greek natural philosopher observed the first lodestones when they were discovered in 600 BC. He was always busy with his research, studying the forces of attraction between magnets and resinous amber.
The black mineral composed of iron and oxygen is called iron hydroxide and formed naturally through volcanism. Today, over 9,600 sites have been documented.

The discovery of lodestones changed the entire world. Thanks to modern research and further investigations into magnetism in physics, magnets are now used in a wide variety of fields. They are used, for example, in the following areas:

• hard drives
• electric motors
• computer monitors
• televisions
• microphones
• speakers

However, the magnetic stones have now also found application in toys, for example building blocks made of magnets, and even in jewelry.

Where were the first magnets used?

Natural lodestone is not a real stone, but rather a magnetized iron oxide. Chinese sources first mention this attractive phenomenon in the 3rd century BC. Lodestone was often called the "loving stone." The inhabitants of China gave the stone this special name because it attracts iron, like a loving mother attracts her children.

One of the oldest known uses of magnetism in history is the compass.
In 200 BC, the Chinese used a compass with a south-facing lodestone spoon. This indicated all four directions. At that time, the original compass was probably used more in connection with feng shui for divination. It was primarily intended to determine the orientation of various buildings.

The compass in the form we know today was first mentioned in the 1st century AD, when a floating needle was used to determine cardinal directions. It had finally been discovered that magnets could also be used to magnetize other objects. An iron needle held near a lodestone also acquires magnetic properties.
The magnetic needle can then be placed on cork. As soon as the cork is placed on the surface of still water, the needle always rotates in two specific directions – one side of the needle points south toward the South Pole, the other side toward the North Pole.

Pierre de Maricourt is considered the founder of the study of magnetism in physics. He was the first to systematically investigate magnetism and recorded his findings on August 8, 1269. He made the following observations:

• like magnetic poles repel each other
• breaking them creates two more magnets

Research and application in modern times

In 1600, scientific research brought further insights with the work of William Gilbert. In his work "De Magnete," he describes the Earth as a large magnet. He discovered the analogy of the Earth's magnetic field to the different types of magnets. Thanks to this principle, he was ultimately able to explain the compass in detail. Although the use of compasses was already widespread, the Scottish physicist Mr. James Clerk Maxwell was the first to establish the connection between magnetism and electricity in 1864. The Maxwell equations he developed are still known today. They form the foundation of electricity and magnetism. Since the 19th century, they have been considered among the most important achievements in physics and mathematics.
Further measurements, such as those by Henry Gellibrand, revealed that the Earth's magnetic field is not static, but slowly changes from time to time.
In the early 19th century, the Magnetic Society was founded in Göttingen and Carl Friedrich Gauss succeeded in proving that the largest part of the Earth's magnetic field originates from the Earth's interior.

Distinguishing between different magnets

There are different types of magnets, each with their own properties. The most common are:

• Ferrite magnet
• Neodymium magnet
• AlNiCo magnet
• Samarium-Cobalt magnet
• Electromagnets

Ferrite magnets

Most people have probably already held a ferrite magnet in their hands, as a 3D fridge magnet.
Ferrite magnets can be recognized by their dark, black, or anthracite color. Hard ferrite magnets are among the most widely used magnetic materials today. The actual raw materials are iron dioxide and strontium carbonate. Isotropic and anisotropic magnets can be made from hard ferrite. Anisotropic ferrite magnets have a significantly higher energy density than isotropic magnets.
This is more than 300 percent higher. Depending on the raw material, they can be divided into barium ferrite and coercive strontium ferrite.
The most important properties of ferrite permanent magnets include their excellent corrosion resistance and high functional capabilities between -40 degrees Celsius and +250 degrees Celsius.
They are also highly resistant to chemicals. Furthermore, they are non-toxic and environmentally friendly, regarding landfill disposal. Ferrite magnets can be categorized differently:

Today, permanent magnets are used in electrical engineering, the automotive and vehicle industries, as well as in medicine, mining, and metallurgy. They also form the core of numerous pinboard magnets and magnetic building blocks used in the office or for hobby purposes.

Neodymium magnets

Neodymium, or "Nd" for short, is one of the rare earth elements and was first extracted by Carl Auer von Welsbach towards the end of the 18th century. Nevertheless, neodymium possesses one crucial and important property.
The discovery of neodymium dates to Carl Friedrich Auer von Welsbach, Carl Gustav Mosander, Per Teodor Cleve, and Lecoq de Boisbaudran. Pure metallic neodymium, however, was not produced until 1925.
In an alloy with boron and iron, neodymium forms the compound NdFeB – this material can be used to produce the strongest permanent magnets today. The neodymium magnet possesses significantly more energy than the steel magnet AlNiCo and is therefore primarily used where strong permanent magnets are needed in the smallest possible space.

Notable examples include:

• generators
• engines
• satellites

Classic neodymium magnets are designated with an "N" followed by a specific number, which indicates their magnetic strength. Typically, the values range between N35 and N50.
One disadvantage of NdFeB magnets is their extreme susceptibility to corrosion.

AlNiCo magnets

AlNiCo magnets are essentially permanent magnets. The steel magnet was developed in 1931. During the production process, ferromagnetic metal pieces are magnetized by a strong magnetic field, transforming them into permanent magnets. Their magnetic force therefore lasts for decades.

AlNiCo magnets are made of aluminum, cobalt, and nickel. Depending on their material composition, they also contain iron, copper, and titanium. Different manufacturing processes can produce both isotropic and anisotropic magnets with different magnetic values. Such permanent magnets can only be machined using diamond tools.
The permanent magnets are particularly resistant to solvents, being resistant only to acid concentrations below 10 percent. Inorganic acids such as citric acid or seawater damage AlNiCo magnets. They also possess high remanence and excellent corrosion resistance. Furthermore, they are unaffected by oils, organic solvents, alcohol, and gasoline. The AlNiCo magnets can be disposed of in an environmentally friendly manner if necessary.

Samarium-cobalt magnets

Samarium-cobalt, abbreviated "SmCo," was developed towards the end of the 1960s. It is an alloy of the rare earth metal samarium with metal cobalt. The abbreviations for this are "Sm" and "Co."
Samarium-cobalt can be produced in two alloy structures: SMCo5 with no iron content, and Sm2Co17 with an iron content of around 20 to 25 percent. In the 1970s, samarium-cobalt was one of the materials with the highest known energy densities. This continued until the discovery of the material neodymium-iron-boron. The powder metal samarium-cobalt is sintered under appropriate heat treatment conditions. This allows for the full density and magnetic orientation to be achieved.

Due to their material composition, the magnets possess an extremely strong magnetic field. In addition, they are particularly resistant to demagnetization. Their high corrosion resistance allows them to be heated to temperatures of up to 300 degrees Celsius.

Electromagnets

Electromagnets differ fundamentally from permanent magnets because their magnetic field is not dependent on magnetic material but is generated by the flow of current.
The discovery of electromagnetism in the 19th century by Hans Christian Oersted laid the foundation for the development of electromagnets.

The operation of electromagnets is based on the fundamental connection between electricity and magnetism, known as electromagnetism. When an electric current flows through a coil of wire (winding), a magnetic field is created around the coil. The strength of this field depends on the current, the number of windings, and the materials used. To enhance the effect of the magnetic field, a core made of ferromagnetic material such as iron is often inserted into the coil. The key to this is the so-called poles, which can be reversed depending on the direction of the current and thus control the operation. Electromagnets are used today in numerous technologies, from precise control in industrial machines to everyday devices such as loudspeakers or door locks. They enable us to use the power of magnetism in a targeted and flexible manner.

The major advantage of electromagnets over traditional permanent magnets is that their magnetic field remains active only as long as current is flowing. This allows them to be switched on and off at will, making them ideal for applications such as electric motors, relays, or industrial lifting magnets.