'Atomic sandwich' to power gen-next, energy-efficient devices

Scientists, including those of Indian origin, have designed new 'atomic sandwiches' - materials that could lead to the next generation of devices that have more computing power and consume 100 times less energy than current electronics.
The material sandwiches together individual layers of atoms, producing a thin film with magnetic polarity that can be flipped from positive to negative or vice versa with small pulses of electricity.
This property may be used to store digital 0's and 1's, the binary backbone that underpins computing devices.
"Before this work, there was only one other room-temperature multiferroic whose magnetic properties could be controlled by electricity," said John Heron, assistant professor at the University of Michigan in the US.

Room-temperature multiferroics are a hotly pursued goal in the electronics field because they require much less power to read and write data than today's semiconductor-based devices.
In addition, their data does not vanish when the power is shut off. Those properties could enable devices that require only brief pulses of electricity instead of the constant stream that's needed for current electronics, using an estimated 100 times less energy.

"Today, about 5 per cent of our total global energy consumption is spent on electronics, and that's projected to grow to 40-50 per cent by 2030 if we continue at the current pace and if there are no major advances in the field that lead to lower energy consumption," said Ramamoorthy Ramesh, from the Lawrence Berkeley National Laboratory in the US.

Researchers, including Hena Das from Cornell University and Rajiv Misra from Pennsylvania State University, started with thin, atomically precise films of hexagonal lutetium iron oxide (LuFeO3), a material known to be a robust ferroelectric, but not strongly magnetic.
Lutetium iron oxide consists of alternating monolayers of lutetium oxide and iron oxide. They then used a technique called molecular-beam epitaxy to add one extra monolayer of iron oxide to every 10 atomic repeats of the single-single monolayer pattern.
"We were essentially spray painting individual atoms of iron, lutetium and oxygen to achieve a new atomic structure that exhibits stronger magnetic properties," said Darrell Schlom, professor at Cornell University in the US.

The result was a new material that combines a phenomenon in lutetium oxide called "planar rumpling" with the magnetic properties of iron oxide to achieve multiferroic properties at room temperature.
Heron explains that the lutetium exhibits atomic-level displacements called rumples. Visible under an electron microscope, the rumples enhance the magnetism in the material, allowing it to persist at room temperature.
The rumples can be moved by applying an electric field, and are enough to nudge the magnetic field in the neighbouring layer of iron oxide from positive to negative or vice versa, creating a "magnetoelectric multiferroic" material whose magnetic properties can be controlled with electricity.

The study was published in the journal Nature.