History of Magnetism: Origin, Discoveries, Scientists, and Applications

We all see magnetism all around us, right from the fridge magnets to a computer hard disk. This article discusses how the word magnetism came into existence and how its understanding has evolved among human beings.

Origin of the word Magnetism

The word magnetism comes from a Greek word “magnētis” which means “stone from Magnesia”, a place in Thessaly, Greece. This place of Greece has the natural deposits of the lodestone (scientific name magnetite or FeO . From the Greek word, it transformed and reached the Latin language as “magnes” and passed on as “magnetism” in old French and finally became “magnetism” in English around the 16 $^{th}$ century.

First understanding and application of magnetic material

A small piece of lodestone was suspended or floated in water to align in the north-south direction. With time, sailors learnt that if the iron needle is magnetized with a lodestone, it can give the same results when suspended in water. This floating magnetized needle in water is known as a compass. The first book on magnetism was published in 1600 by William Gilbert, De Magnete, Magneticisque Corporibus, et de
Magno Magnete Tellure (On the Loadstone and Magnetic Bodies and on the Great Magnet the Earth). In this book, this English physician of Elizabeth I laid the foundations of the Earth being a giant magnet and studied loadstone and its relation with electricity in its early stages. William Gilbert is also called the father of magnetism. During his observation of the lodestone, after removing the lodestone from the external field, it rotated along the direction of the external field. This phenomenon persists at the quantum level in the single-spin moment behaviour.

Ancient exploration of magnetic lodestone

Sailors used this magnetic loadstone to magnetize small iron needles to get the north and south directions when the sun and stars are not visible. The earliest use of these compass needles was in China from the 2 BCE to the 1 Century CE. While trade from China, India, and Islamic mariners likely introduced this directional equipment. In Indian Sanskrit scripts, it was known as “matsya-yantra” as floating iron needles of fish shape were used. From the Islamic world, it reached Europe. The first account of the compass in European literature comes in the 12 century in the book “De naturis rerum”, by Alexander Neckam.

Magnetism as a perspective of living beings on Earth

Magnetism is also used by living beings for navigation, like the migration of birds, crabs, and certain worms. Earth’s magnetic field has not been static but has evolved with time, and even flipped its orientation, as geological rock specimens explain. This Earth’s magnetic field is not only used in adaptation of the living beings, but also one of the reasons of life on Earth, and a natural phenomenon, Aurora, which forms when the magnetic field protects living creatures from the Sun’s life-threatening solar flares.

Contribution of various scientists in understanding magnetism

Various scientists contributed to understanding the fundamentals and applications of magnetism to revolutionize the world at each stage. The discovery of the loadstone laid the path of the field of magnetism in ancient times. In the \(18^{th}\) Century, extensive studies on this phenomenon by Ørsted, Ampère, Gauss, Faraday, and Henry were performed that relate electricity and magnetism and explain the co-dependency. The theoretical understanding of electromagnetism comes from Maxwell’s equations by James Clerk Maxwell, a \(19^{th}\) century Scottish scientist. These equation plays an important role in electromagnetism as Newton’s laws in classical mechanics. The experimental proof of Maxwell’s equations was done by Heinrich Hertz by the generation and detection of radio waves (electromagnetic waves).

How the magnetic materials lose their magnetism after heating to a certain temperature, as understood and stated by Pierre Curie, is known as the Curie temperature. The scientific explanation of paramagnetism and diamagnetism was given using statistical mechanics that were evolving in the \(19^{th}\) century by Paul Langevin, a French scientist. Although scientists were trying to understand magnetism, the ferromagnetic materials were still not ready to be deciphered with classical physics theories, as the magnetic properties have more duality than just induced from dynamic electric fields.

Arrival of Quantum Mechanics

As quantum physics evolved, a better understanding of superposition, quantization of the energy levels in atoms, and spin operators with a probabilistic approach, symmetric and asymmetric wavefunctions in physics built the fundamentals to decipher this Rosetta stone of the load stone. Modern physicists like Pierre Weiss, Werner Heisenberg, Lev Landau, Louis Néel, and Bloch used quantum tools to explain exchange interaction in the ferromagnets, phase transition from the magnetic to non-magnetic states, canting of magnetic moments, and dynamic magnetic fields with quanta magnons. End of the \(20^{th}\) century and \(21^{st}\) century scientists discovered phenomena like Giant magnetoresistance (GMR), exchange bias, topological magnetic texture, and a new subfield of magnetism, spintronics, with the power to make this century much energy efficient in terms of computing and the storage which is needed in this era of Artificial Intelligence.

References

1. Coey, John MD. Magnetism and magnetic materials. Cambridge university press, 2010.
2. Neckam, Alexander. De naturis rerum, libri duo: With the Poem of the Same Author, De laudibus divinae sapientiae. Cambridge University Press, 2012.
3. Chikazumi, Sōshin, and Chad D. Graham. Physics of ferromagnetism. No. 94. Oxford university press, 1997.