Physicists turn ‘worthless’ pyrite into valuable magneto

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Pyrite may be the “gold of fools” in movies and in the popular imagination, but for science, it may be worth more than its weight. Thanks to a team of researchers at the University of Minnesota, it became the first material to become magnetic artificially.

The achievement is unprecedented; it has never been achieved before to “create” magnetism in materials that do not have this property. To do this, the researchers used a technique called “electrolyte modulation”, in which purified pyrite crystals are dipped in an ionic solution.

The magic happens when the researchers apply to the 1 volt solution – voltage less than that of a common cell, but enough to cause the positively charged molecules of the solution to group between the liquid and the iron contained in the pyrite. The result: a magnetized surface. To reverse the process, simply remove the electricity from the solution.

Cheap and nontoxic solar cells

“We were surprised that it worked. When applying the voltage, what we did was pour electrons into the material. If we get sufficiently high concentrations of these particles, the material will spontaneously want to become ferromagnetic, which we have been able to understand from experience. The results obtained have a lot of potential. We believe it is possible to do the same with other materials besides iron sulfide,” said physicist Christopher Leighton, lead researcher of the study now published in the journal Science Advances.

He and his colleagues have been interested in pyrite for more than a decade, studying how to make the mineral efficient enough to be used in the production of low-cost solar cells (among the byproducts of oil extraction is sulfur, which makes the substance abundant and inexpensive)

“Most people who know magnetism would say it is impossible to electrically transform a non-magnetic material into a magnetic one. When we looked a little deeper, we saw potential and made it happen,” says the researcher.

Despised, but not by science

“We turned our attention to this material precisely to figure out how to use it initially in cheap and non-toxic solar cells. At the same time, we were working with magnetoionics, studying how to use electrical voltages to control magnetic properties of materials, aiming at possible applications in magnetic data storage devices. At some point, we realized that this would be the perfect convergence of two areas of research,” Leighton says.

The goal now is to create and manipulate the magnetism of other materials through low voltage loads, critical to making the manipulated material more energy efficient. The next step will be to employ higher temperatures in the process and with other materials to confirm their potential for use in electronic devices.

Various uses in study

Pyrite has long aroused interest in being cheap and with possible applications in the electronics industry. In 2014, a team of researchers from the Massachusetts Institute of Technology (MIT) conducted the first detailed examination of the electronic properties of the material’s surface, aiming at its future use in spintronic devices (in which electrons carry information).

Solar cells are also the focus of researchers at the University of California, who are investing in the production of pure colloidal pyrite nanocrystals, to be applied in ink form in large and inexpensive solar cell modules. The University of Kansas is also studying its use as a conductor for photovoltaics and high-density cathode energy material in batteries.

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