Which metals have magnetism?

 　　Magnetic metals include:

　　iron

　　nickel

　　cobalt

　　Some rare earth metal alloys

　　These magnetic metals belong to the following categories:

　　Permanent magnet

　　Electromagnet

　　Neodymium magnet

　　Permanent magnet

　　When people think of magnets, they usually think of permanent magnets. These are objects that can be magnetized to generate a magnetic field. The most common example is a refrigerator magnet, which is used to store notes on our refrigerator door.

　　The most common metals used for permanent magnets are iron, nickel, cobalt, and some rare earth metal alloys.

　　There are two types of permanent magnets: permanent magnets from "hard" magnetic materials and permanent magnets from "soft" magnetic materials. Hard "magnetic metals often remain magnetized for a long time. Common examples include:

　　Aluminum nickel cobalt alloy, an iron alloy with aluminum, nickel, and cobalt. Aluminum nickel cobalt alloy can be used to manufacture sturdy permanent magnets. They are widely used in industry and consumer electronics. For example, in large motors, microphones, speakers, electric guitar pickups, and microwave ovens.

　　Ferrite, a ceramic compound composed of iron oxide and other metallic elements. Ferrite is used for refrigerator magnets and small electric motors.

　　Soft "magnetic metals can be magnetized, but they quickly lose their magnetism. Common examples are ferrosilicon alloys and nickel iron alloys. These materials are commonly used in electronic products, such as transformers and magnetic shields.

　　Electromagnet

　　Electromagnets are made of copper wire coils wound around iron, nickel, or cobalt cores. When current passes through the coil, a magnetic field is generated, but when the current stops, the magnetic field disappears. Electromagnets require electricity to work. Their purpose is to change the magnetic field intensity by controlling the current in the wire.

　　Electromagnets are commonly used in electric motors and generators. They are all based on the scientific principle of electromagnetic induction discovered by scientist Michael Faraday in 1831, which believes that moving current will produce magnetic field, and vice versa. In an electric motor, current generates a magnetic field that moves the motor. In a generator, external forces such as wind, flowing water, or steam cause the shaft to rotate, and the shaft moves a group of magnets around the winding wire, generating an electric current.

　　Electromagnets are also used as switches in flick relays, for telephone exchanges, railway signals, and traffic lights.

　　The garbage dump crane is also equipped with an electromagnet for easy picking up and lowering of large vehicles. These electromagnets are in the form of circular plates installed at the end of the crane.

　　A modern train system called magnetic levitation (abbreviated as maglev) uses electromagnets to levitate trains above the tracks. This reduces friction and allows the train to travel at extremely fast speeds.

　　Advanced applications of electromagnets include magnetic resonance imaging (MRI) machines and particle accelerator (such as the Large Hadron Collider).

　　Neodymium magnet

　　Neodymium magnet is a rare earth magnet composed of alloys of neodymium, iron, and boron. They were designed by General Motors and Sumitomo Special Metals in 1982. Neodymium magnet is the strongest type of permanent magnet available on the market. When strong permanent magnets are needed, especially in cordless tool motors, hard drives, and magnetic fasteners, they are used.

　　Convert non-magnetic metals into magnets

　　Copper and manganese usually have no magnetism. However, a groundbreaking new technology developed by Oscar Cespes of the University of Leeds in the UK has transformed copper and manganese into magnets.

　　Setspedes and his team fabricated thin films of copper and manganese on carbon structures, known as buckyballs. When an external magnetic field is applied and removed, the film retains 10% of the magnetic field. This new technology aims to provide a more biocompatible and environmentally friendly MRI machine manufacturing method.

　　Other possible applications include for wind turbines. Wind turbines currently use iron, cobalt, nickel, and rare earth elements. But these elements are both expensive and difficult to extract. This breakthrough opens up the possibility of cheaper alternatives.