A four-state magnetic tunnel junction for novel spintronics applications

August 21, 2020

A tunnel junction is a device consisting of two conducting layers separated by an insulating layer. Classically, the resistance for driving current across an insulating layer is infinite; however, when the insulating layer is thin (~ 1-2 nanometers), charge carriers may tunnel through the insulating layer, due to their quantum nature. When the conducting layers are magnetic, a magnetic tunnel junction (MTJ), whose resistance depends on the magnetic configurations, is obtained. Current MTJs have only two resistance states as they support either parallel or anti-parallel magnetic configurations of the two magnetic layers. The two-state MTJ has been playing a central role in spintronics, a branch of electronics that uses the magnetic moment associated with the spin of the electron in addition to the electron charge used in traditional electronics. Thus, for instance, the two-state MTJ is the main building block of the magnetic random access memory (MRAM).

Now, researchers from Bar-Ilan University's Department of Physics and Institute of Nanotechnology and Advanced Materials, together with a group from Instituto Superior Tecnico (IST), Universidade de Lisboa and INESC Microsystems and Nanotechnologies, have introduced a new type of MTJ with four resistance states, and successfully demonstrated switching between the states with spin currents. The increased number of states is achieved by replacing one of the magnetic layers with a structure in the form of two crossing ellipses.

"As it has recently been shown that structures in the form of N crossing ellipses can support two to the power of 2N states, the current results may pave the way to MTJs with much larger number of resistance states," says Prof. Lior Klein, Chairman of Bar-Ilan University's Department of Physics, who led the Bar-Ilan group including Dr. Shubhankar Das, Ariel Zaig, and Dr. Moty Schultz. Prof. Susana Cardoso led the group from Instituto Superior Tecnico (IST), Universidade de Lisboa and INESC Microsystems and Nanotechnologies, together with Dr. Diana C. Leitao. "Such MTJs may enable novel spintronics devices, e.g., multi-level MRAM which stores data much more densely, or neuromorphic memory that meets artificial intelligence challenges in performing cognitive tasks," adds Klein.
-end-
This research appears as an Editor's Pick article in an August issue of Applied Physics Letters.

Bar-Ilan University

Related Spintronics Articles from Brightsurf:

A four-state magnetic tunnel junction for novel spintronics applications
Researchers have introduced a new type of MTJ with four resistance states, and successfully demonstrated switching between the states with spin currents.

Ultrafast electrons in magnetic oxides: A new direction for spintronics?
Special metal oxides could one day replace semiconductor materials that are commonly used today in processors.

Efficient valves for electron spins
Researchers at the University of Basel in collaboration with colleagues from Pisa have developed a new concept that uses the electron spin to switch an electrical current.

Magnetic memory states go exponential
Researchers showed that relatively simple structures can support exponential number of magnetic states - much greater than previously thought - and demonstrated switching between the states by generating spin currents.

New breakthrough in 'spintronics' could boost high speed data technology
Scientists have made a pivotal breakthrough in the important, emerging field of spintronics -- which could lead to a new high speed energy efficient data technology.

A path to new nanofluidic devices applying spintronics technology
Japanese scientists have elucidated the mechanism of the hydrodynamic power generation using spin currents in micrometer-scale channels, finding that power generation efficiency improves drastically as the size of the flow is made smaller.

Extensive review of spin-gapless semiconductors: Next-generation spintronics candidates
An Australian has published an extensive review of spin-gapless semiconductors (SGSs), a new class of 'zero bandgap' materials which have fully spin polarised electrons and holes, and first proposed in 2008 by the review team's lead, Professor Xiaolin Wang (University of Wollongong).

Graphene and 2D materials could move electronics beyond 'Moore's Law'
A team of researchers based in Manchester, the Netherlands, Singapore, Spain, Switzerland and the USA has published a new review on a field of computer device development known as spintronics, which could see graphene used as building block for next-generation electronics.

Toward a more energy-efficient spintronics
In order to generate and detect spin currents, spintronics traditionally uses ferromagnetic materials whose magnetization switching consume high amounts of energy.

Computing with molecules: A big step in molecular spintronics
Chemists and physicists at Kiel University joined forces with colleagues from France, and Switzerland to design, deposit and operate single molecular spin switches on surfaces.

Read More: Spintronics News and Spintronics 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.