Scientists have discovered a possible way to activate an unusual form of magnetism in an ultrathin material, a breakthrough that could eventually help create smaller, faster and more energy efficient computer memory.
Researchers from Rice University and collaborating institutions found that ruthenium dioxide a material normally considered nonmagnetic in its bulk form, can show signs of a recently proposed magnetic state known as altermagnetism when it is made only a few atomic layers thick and placed under strain.
The findings were published in the journal Science Advances.
Altermagnetism is considered a potentially important new form of magnetic behavior. Unlike conventional ferromagnets, where electron spins align in the same direction, or antiferromagnets, where neighboring spins cancel each other out, altermagnetic materials can display more complex spin patterns while producing useful electronic properties.
To investigate the material, researchers studied its spin texture, which describes how the magnetic spins of electrons are arranged inside a material. The team used a highly advanced technique called spin-resolved angle-resolved photoemission spectroscopy to examine the electron behavior in ultrathin ruthenium dioxide films.
Their results showed spin patterns consistent with unconventional magnetism, suggesting that ruthenium dioxide can behave very differently when reduced to an extremely thin form.
The researchers found that strain played a crucial role. When pressure was applied to the atomic structure of the ultrathin material, unusual magnetic behavior emerged. Without this strain, the material did not show clear signs of altermagnetism.
This means scientists may eventually be able to control magnetism by adjusting the strain inside a material, similar to using a tuning knob.
Such control could have major applications in spintronics, a growing field of electronics that uses the spin of electrons, rather than only their electrical charge to process and store information.
Spintronics could lead to faster computer memory, lower energy consumption and new types of electronic devices.
Ruthenium dioxide has been at the center of a long scientific debate because researchers struggled to determine whether its bulk form was magnetic. Scientists eventually reached a general consensus that the larger, bulk material does not display magnetism.
The new research, however suggests that changing the material thickness and applying strain can dramatically alter its properties.
Researchers say the discovery highlights how quantum materials can behave in unexpected ways when engineered at the atomic scale.
The ability to potentially switch altermagnetism on and off using strain could open new possibilities for future quantum technologies, advanced electronics and next generation RAM systems.