Researchers at the University of Central Florida in the United States say they have found the first experimental proof of altermagnetism, a third form of magnetism that sits outside the familiar ferromagnetism and antiferromagnetism. In a study published in Nature Communications, the team reports that they uncovered the magnetic state using a specially layered, sandwich-shaped material made of cobalt, tantalum and selenium. The discovery is being described as a major milestone for modern electronics and spintronics technology.

According to the researchers, conventional ferromagnets carry north and south poles, with the magnetic fields of their particles aligned in the same direction, as seen in fridge magnets. The stray fields produced this way, however, can interfere with the operation of computer chips. In antiferromagnets, by contrast, the magnetic fields face opposite directions and cancel one another out, leaving no north or south pole. Scientists had been pursuing altermagnetism in order to combine the advantages of both forms.

Commenting on the work, scientist Madhav Neupane said the new material can generate spin current without the negative effects caused by stray fields. The researchers created a cobalt tantalum selenide crystal, combining cobalt, tantalum and selenium, and prepared it by baking or heating it at temperatures above about 900 degrees Celsius for two weeks. In this material, cobalt atoms are arranged between layers of metallic tantalum and non-metallic selenium in a way that allows them to influence electrons. Using quantum modelling methods and ARPES technology, the scientists confirmed that the material can split electrons on the basis of their spin, or rotation.

Milo Sprague, the lead author of the study, said there has long been debate over the interaction between altermagnetic theory and spin-polarised electronic states. The new versatile material, he noted, will open a fresh path for scientists to unlock that mystery. Looking ahead, layered altermagnets of this kind could play a major role in spintronics, helping to increase data storage capacity and strengthen information security in the future.

Source: Science Alert