Scientists in the US have found a new way to change the magnetic behavior of tiny crystals after discovering that squeezing them between two metal plates can change their properties.
The experiments were conducted at the Department of Energy’s (DOE) Oak Ridge National Laboratory (ORNL) in Tennessee. To test the method, the team examined two materials from a new class of magnets called alter magnets.
Alter magnets are a third fundamental class of magnetic materials that combine properties of ferromagnets and antiferromagnets. They reportedly have zero net magnetization like antiferromagnets and exhibit strong momentum-dependent spin polarization and band splitting like ferromagnets.
Laboratory tests showed that mechanical pressure can change the materials’ magnetic domains and electron flow. This could enable better control of magnetism in future electronic devices, according to the team.
Pressure changes magnetism
For the experiments, the research team used tiny crystals made of manganese telluride (MnTe) and iron sulfide (FeS). They then placed the crystals between two titanium plates and applied mechanical pressure.
They then examined the materials using neutron diffraction at ORNL’s Spallation Neutron Source (SNS), which produces some of the most intense pulsed neutron beams in the world. The facility uses an accelerator to fire short pulses of protons at a liquid mercury target.
This releases neutrons, which scientists use to study materials and their properties. It showed how pressure affected the magnetic structure of the crystals.
According to ORNL, even a small amount of mechanical pressure was enough to change the populations of these domains. The researchers also saw changes in an electrical response known as the anomalous Hall effect (AHE), which is related to the materials’ magnetic properties.
The anomalous Hall effect (AHE) occurs when an electric current flows through a magnetic material and creates a voltage across it. Unlike the common Hall effect, it is driven by the material’s internal magnetic properties rather than an external magnetic field.
Applications in electronics
The results suggest that pressure may be a simple way to control magnetism and electron flow in alter magnets. The researchers reported this in two separate studies.
Feng Ye, PhD, an ORNL neutron scientist and co-author of both studies, emphasized the role of neutron scattering in understanding these magnetic changes. “The exciting thing is that a creative experimental idea, a small mechanical pressure between two plates, can reveal completely new magnetic behavior and advance the field,” Ye emphasized in a press release.
Ye added that the findings could be particularly important for an emerging field called spintronics, also known as spin electronics. The field uses the spin of electronics, not just their electrical charge, to store and process information.
The technology could lead to faster and more energy-efficient electronic devices, such as advanced storage and computing systems. “By controlling the magnetic domains, we can directly influence the transport behavior, and this opens the door to exploring these materials for spintronic technologies,” said Pengcheng Dai, PhD, a researcher at Rice University and former neutron scientist at ORNL.
