Method in the magnets

Jarillo-Herrero and Xu aren’t the only ones studying 2D magnets. In late April, another group of researchers published their observations of magnetism in an ultrathin crystal made of chromium, germanium and tellurium2. A true 2D magnet would retain its magnetism at the single-atom layer, but this ultrathin crystal was only magnetic at multiple layers.

Both results are significant, however, says Nitin Samarth, a condensed-matter physicist at Pennsylvania State University in University Park, who was not involved with the work. Samarth wrote a commentary accompanying the recent studies. Before these discoveries, “we never had a generic method for creating truly 2D magnetic materials,” he says. Researchers have been trying to make and study ultrathin magnets since the 1970s, but all the resulting materials contained holes and bumps, and weren’t truly 2D.

Physicists would like to find a 2D magnet that works at room temperature and that doesn’t have to be protected from oxygen, so that it might eventually be used in consumer electronics. For now, Jarillo-Herrero and Xu are looking for other 2D magnets in chromium triiodide’s chemical family, and further exploring the one they’ve created.

Jarillo-Herrero wants to layer the 2D magnet with a 2D superconductor and see what happens. In a magnet, the electron spins are all aligned; in a superconductor, they’re arranged in opposite pairs. “Does the superconductor destroy the ferromagnet, or does the ferromagnet destroy the superconductor?” he wonders. “It was just not possible to do this experiment before.”

It’s too early to tell whether there’s something fundamentally new here in terms of the physics, says Samarth. But now that physicists can experiment with 2D magnets, they’re excited to try to find out.

Nature