New insights into semiconductors for spintronic applications from hard X-ray photoemission

August 30, 2018 by Andy Fell, UC Davis

A standing wave will interact with different atoms in the material depending on the plane of the scan (left). On the right, atoms are excited differently depending on how they interact with the standing wave of hard X-rays. Credit: UC Davis
"Spintronics" holds promise for new types of devices for information processing and data storage, with ones and zeros being stored in the spin state of electrons as well as their electric charge. Such devices could be faster and more energy efficient than current electronics.

Dilute magnetic semiconductors such as manganese-doped arsenide are a promising material for spintronics, said Slavomir Nemsak, staff researcher at the Lawrence Berkeley National Laboratory and former postdoc in the UC Davis Department of Physics, working with Professor Charles Fadley and Adjunct Professor Claus Schneider. They have but are not themselves metals. They are called "dilute" because the dopant makes up a small amount (a few percent) of the semiconductor material.

In a new study published Aug. 17 in Nature Communications, Nemsak, Fadley, Schneider and colleagues demonstrate the use of new techniques in X-ray spectroscopy to illuminate the internal structure of manganese-doped gallium arsenide.

They used a technique called hard X-ray , or HARPES, combined with standing-wave excitation to obtain the unique and unprecedented look inside these promising new materials.

Standing-wave excitation allowed the researchers to enhance the electrical fields inside a material, creating peaks and troughs in each atomic layer. They could then determine which sites in a layer were occupied by gallium, arsenic or . The team combined this with the HARPES data, which gives information on how electrons determining the electric and optical properties behave in the material.

Connecting electronic states to elements

"We can use the standing wave to enhance the signal from gallium or arsenic layers, and we found that manganese was always present at the position of gallium atoms all the way from the bulk of material to its surface layers." Nemsak said. "We were also able to identify the changes in the electronics of the material caused by the presence of manganese dopant and connect the individual electronic states to their elemental origin."

This is the first time it has been possible to get this kind of information on structure and electronic properties from materials, Nemsak said. The technique should be applicable to any kind of material, including metals, semiconductors and insulators, and superconductors, he said.

The work with "hard" or high-energy X-rays was conducted using the Diamond Light Source at Didcot, U.K. This kind of study is currently possible with only a handful of facilities worldwide, including in the near future the Advanced Light Source at the Berkeley Lab.

Explore further: New finding could pave way to faster, smaller electronics

More information: Slavomír Nemšák et al. Element- and momentum-resolved electronic structure of the dilute magnetic semiconductor manganese doped gallium arsenide, Nature Communications (2018). DOI: 10.1038/s41467-018-05823-z

Related Stories

New finding could pave way to faster, smaller electronics

October 23, 2012

University of California, Davis, researchers for the first time have looked inside gallium manganese arsenide, a type of material known as a "dilute magnetic semiconductor" that could open up an entirely new class of faster, ...

Recommended for you

New insights into magnetic quantum effects in solids

January 23, 2019

Using a new computational method, an international collaboration has succeeded for the first time in systematically investigating magnetic quantum effects in the well-known 3-D pyrochlore Heisenberg model. The surprising ...

Rapid and continuous 3-D printing with light

January 22, 2019

Three-dimensional (3-D) printing, also known as additive manufacturing (AM), can transform a material layer by layer to build an object of interest. 3-D printing is not a new concept, since stereolithography printers have ...

Scientists discover new quantum spin liquid

January 22, 2019

An international research team led by the University of Liverpool and McMaster University has made a significant breakthrough in the search for new states of matter.

Researchers capture an image of negative capacitance in action

January 21, 2019

For the first time ever, an international team of researchers imaged the microscopic state of negative capacitance. This novel result provides researchers with fundamental, atomistic insight into the physics of negative capacitance, ...

0 comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.