This is a schematic of a platinum transistor with a paramagnetic ionic liquid gate. Image: L. Liang.
This is a schematic of a platinum transistor with a paramagnetic ionic liquid gate. Image: L. Liang.

Physicists at the University of Groningen in the Netherlands have induced magnetism in platinum using an electric field created by a paramagnetic ionic liquid. As the electric field only affects the surface of the platinum, this creates a switchable two-dimensional (2D) ferromagnet. The study is reported in a paper in Science Advances.

Platinum is commonly used in jewellery and electronics. Although this precious metal looks great and is an excellent conductor, it has no magnetic properties. But now physicists at the University of Groningen have managed to induce ferromagnetic states on the surface of a thin film of platinum.

“You can tune magnets electrically by changing the number of carriers inside, which is one of the key ideas in spintronics. But so far, no one could generate magnets like that,” says Justin Ye, chair of the Device Physics of Complex Materials group at the University of Groningen.

Lei Liang, a postdoc in Ye's research group and first author of the paper, built a device that could induce ferromagnetism in non-magnetic platinum, using a field effect generated by gating through an ionic medium known as an ionic liquid. “The key here is that we used a paramagnetic ionic liquid, a new type of ionic liquid which we synthesized ourselves,” explains Ye.

Applying an electric field to the ionic liquid causes ions to move to the surface of the platinum, carrying charge and magnetic moment. Both affect the surface layer of the platinum film, creating an atomically thin layer of magnetic platinum.

“We were able to show that this is really a 2D magnet, and the magnetic state can extend to the room temperature,” says Ye. “It is amazing that we could still add new properties to such a well-known material.”

Recently, several 2D magnets have been isolated from layered compounds, but most are insulators and they are only magnetic at very low temperatures. Making 2D magnets from a conductor could prove useful in spintronics, a promising new type of electronics based on the magnetic moment (or spin) of electrons. This new discovery means that magnetism can now be switched on and off in a conductor, which could lead to the development of devices that can simultaneously control charge and spin.

This story is adapted from material from the University of Groningen, with editorial changes made by Materials Today. The views expressed in this article do not necessarily represent those of Elsevier. Link to original source.