Ultrafast electrons in magnetic oxides: A new direction for spintronics?

August 19, 2020

Special metal oxides could one day replace semiconductor materials that are commonly used today in processors. Now, for the first time, an international team of researchers from Martin Luther University Halle-Wittenberg (MLU), the University of Kaiserslautern and the University of Fribourg in Switzerland was able to observe how electronic charge excitation changes electron spin in metal oxides in an ultrafast and inphase manner. The study was published in the journal Nature Communications.

In modern semiconductor electronics, the first key step in every transistor is to lift electrons over the so-called band gap in the semiconductor. Electrons have to move through a material that is, in actual fact, non-conductive. "After they have been excited across the band gap, the moving electric charges of the electrons generate the currents that are used in information processing. These currents can cause processors to become hot, leading to energy loss," explains Professor Wolf Widdra from the Institute of Physics at MLU.

Spintronics attempts to solve this problem with the help of so-called spin. This is the intrinsic angular momentum of an electron that produces the magnetic moment, thereby generating the magnetism that is used in information processing. The coupling of electronic and magnetic properties determines the functionality. "Magnetic oxides are an important class of materials for spintronics because they don't transfer electron current, only magnetic information," says Widdra, who led the study as part of the joint Collaborative Research Centre CRC/TRR 227 "Ultrafast Spin Dynamics" at MLU and Freie Universität Berlin. Until recently, however, it hadn't been clear how the electron transfer across the band gap coupled with the spin of the magnetic oxide. The team has now successfully observed this process and has developed a new theory for it. Groups of theoretical and experimental physicists joined forces to tackle this issue.

Using a state-of-the-art, ultra-short pulse laser, the researchers were able to excite an electron to lift it across the band gap in nickel oxide. They also observed how the information was then transferred to the magnetic system. This enabled the team to identify a previously unknown ultrafast coupling mechanism that occurs on a femtosecond scale, i.e. a quadrillionth of a second. "The complex many-body properties generated through the excitation of the electron by the laser have revealed this surprising observation but also made us think long and hard about how to interpret it correctly," adds Widdra.

According to the physicist, the findings now pave the way for ultrafast spintronics. This should facilitate the development of new ultra-fast storage systems and information technologies in the future.
-end-
The study was funded by the Deutsche Forschungsgemeinschaft (German Research Foundation, DFG), the Swiss National Science Foundation and the European Research Council.

Martin-Luther-Universität Halle-Wittenberg

Related Semiconductor Articles from Brightsurf:

Blue phosphorus: How a semiconductor becomes a metal
Blue phosphorus, an atomically thin synthetic semiconductor, becomes metallic as soon as it is converted into a double layer.

A new method to measure optical absorption in semiconductor crystals
Tohoku University researchers have revealed more details about omnidirectional photoluminescence (ODPL) spectroscopy - a method for probing semiconducting crystals with light to detect defects and impurities.

Medical robotic hand? Rubbery semiconductor makes it possible
A medical robotic hand could allow doctors to more accurately diagnose and treat people from halfway around the world, but currently available technologies aren't good enough to match the in-person experience.

Laser allows solid-state refrigeration of a semiconductor material
A team from the University of Washington used an infrared laser to cool a solid semiconductor by at least 20 degrees C, or 36 F, below room temperature, as they report in a paper published June 23 in Nature Communications.

Scientists create smallest semiconductor laser
An international team of researchers announced the development of the world's most compact semiconductor laser that works in the visible range at room temperature.

Clemson researcher's novel MOF is potential next-gen semiconductor
Clemson professor Sourav Saha demonstrated a novel double-helical metal organic framework architecture in a partially oxidized form that conducts electricity, potentially making it a next-generation semiconductor.

A gold butterfly can make its own semiconductor skin
A nanoscale gold butterfly provides a more precise route for growing/synthesizing nanosized semiconductors that can be used in nano-lasers and other applications.

Scientists pioneer new generation of semiconductor neutron detector
In a new study, scientists have developed a new type of semiconductor neutron detector that boosts detection rates by reducing the number of steps involved in neutron capture and transduction.

Scientists see defects in potential new semiconductor
A research team has reported seeing, for the first time, atomic scale defects that dictate the properties of a new and powerful semiconductor.

Bending an organic semiconductor can boost electrical flow
Slightly bending semiconductors made of organic materials can roughly double the speed of electricity flowing through them and could benefit next-generation electronics such as sensors and solar cells, according to Rutgers-led research.

Read More: Semiconductor News and Semiconductor Current Events
Brightsurf.com is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to Amazon.com.