Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Insight into inner magnetic layers

18.02.2015

Measurements at BESSY II have shown how spin filters forming within magnetic sandwiches influence tunnel magnetoresistance -- results that can help in designing spintronic component-

In doing so, the teams enhanced our understanding of processes that are important for future TMR data storage devices and other spintronic components. Their results have now been published in Nature Communications (DOI: 10.1038/ncomms7306).


The insulating LFO-layer in its normal state is antiferromagnetically ordered (AFM) and has no ferromagnetic domains. Due to the proximity to the ferromagnetic LSMO, ferromagnetic domains develop (white arrows) at the interface, pointing into the opposite direction of the LSMO-layer.

Credit: HZB

Layers of magnetic materials are found in every hard drive and in every read/write head today. These are sandwiches made of complex heterostructures in which the different layers have typical thicknesses of only a few nanometres. An effect of quantum physics called tunnel magnetoresistance (TMR) is critical for their operation. It occurs when two ferromagnetic layers are separated from one another by an insulating layer several plies of atoms thick, like cheese between two slices of bread. As long as the magnetisation in both "slices" is parallel, the electrons can tunnel through the "cheese", i.e. the device resistance is low. However, if the magnetisation changes in one of the layers, the electrons can no longer tunnel through the middle layer, i.e. the resistance is high. In this way, the electrical resistance can be precisely controlled through the influence of a magnetic field on one of the two outer layers, and be associated with the binary values of zero and one used for calculations.

New effect observed

The teams from France, Spain and HZB have now discovered that in such sandwiches combining different transition metal oxides, new interfacial effects can strongly influence the amplitude of the TMR This is what the French team under Manuel Bibes and Agnès Barthelemy of the Unité de Physique, CNRS/Thales, Palaiseau (working in collaboration with the team of Jacobo Santamaria in Madrid) had initially observed in measuring the electron transport characteristics. They were researching a system of two LSMO (La0.7Sr0.3MnO3) layers that were separated by a very thin layer of LFO (LaFeO3). The LSMO layers were ferromagnetic while the LFO insulating layer was anti-ferromagnetic.

New magnetic order at the interface

Measurements using the ALICE chamber and from the XPEEM instrument in beamline UE49 at BESSY II have clearly shown what is happening in the interface between the ferromagnetic layers and the anti-ferromagnetic inner layer. The teams were able to decode how each of the magnetic elements manganese and iron were oriented at the interfaces using the XPEEM instrument. "We saw how new magnetic phases arise at the boundaries that function like spin filters", explained Sergio Valencia, who heads the HZB team. "Put simply: the iron atoms near the interface are influenced by the manganese magnetic moments; they then orient their magnetic moments antiparallel to those of the manganese atoms and thus form ferromagnetic domains. We have thus demonstrated experimentally for the first time that ferromagnetic domains can be induced in non-ferromagnetic barrier layers." The French team carried out subsequent calculations of how these kinds of spin filters effect the tunnel magnetoresistance and could reproduce the experimental data.

"These kinds of complex oxide heterostructures as we investigated here could play an important role in future spintronics", says Valencia. The results that have now been published in Nature Communications explain an important process that has not been taken into account so far, and they therefore help in designing tunnel barriers with the desired properties.

###

To the publication in Nature Communications: "Insight into spin transport in oxide heterostructures from interface-resolved magnetic mapping" DOI: 10.1038/ncomms7306

Media Contact

Dr. Sergio Valencia Molina
sergio.valencia@helmholtz-berlin.de
49-308-062-15619

http://www.hmi.de 

Dr. Sergio Valencia Molina | EurekAlert!

More articles from Materials Sciences:

nachricht Hidden talents: Converting heat into electricity with pencil and paper
20.02.2018 | Helmholtz-Zentrum Berlin für Materialien und Energie

nachricht Contacting the molecular world through graphene nanoribbons
19.02.2018 | Elhuyar Fundazioa

All articles from Materials Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: In best circles: First integrated circuit from self-assembled polymer

For the first time, a team of researchers at the Max-Planck Institute (MPI) for Polymer Research in Mainz, Germany, has succeeded in making an integrated circuit (IC) from just a monolayer of a semiconducting polymer via a bottom-up, self-assembly approach.

In the self-assembly process, the semiconducting polymer arranges itself into an ordered monolayer in a transistor. The transistors are binary switches used...

Im Focus: Demonstration of a single molecule piezoelectric effect

Breakthrough provides a new concept of the design of molecular motors, sensors and electricity generators at nanoscale

Researchers from the Institute of Organic Chemistry and Biochemistry of the CAS (IOCB Prague), Institute of Physics of the CAS (IP CAS) and Palacký University...

Im Focus: Hybrid optics bring color imaging using ultrathin metalenses into focus

For photographers and scientists, lenses are lifesavers. They reflect and refract light, making possible the imaging systems that drive discovery through the microscope and preserve history through cameras.

But today's glass-based lenses are bulky and resist miniaturization. Next-generation technologies, such as ultrathin cameras or tiny microscopes, require...

Im Focus: Stem cell divisions in the adult brain seen for the first time

Scientists from the University of Zurich have succeeded for the first time in tracking individual stem cells and their neuronal progeny over months within the intact adult brain. This study sheds light on how new neurons are produced throughout life.

The generation of new nerve cells was once thought to taper off at the end of embryonic development. However, recent research has shown that the adult brain...

Im Focus: Interference as a new method for cooling quantum devices

Theoretical physicists propose to use negative interference to control heat flow in quantum devices. Study published in Physical Review Letters

Quantum computer parts are sensitive and need to be cooled to very low temperatures. Their tiny size makes them particularly susceptible to a temperature...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

2nd International Conference on High Temperature Shape Memory Alloys (HTSMAs)

15.02.2018 | Event News

Aachen DC Grid Summit 2018

13.02.2018 | Event News

How Global Climate Policy Can Learn from the Energy Transition

12.02.2018 | Event News

 
Latest News

Rare find from the deep sea

20.02.2018 | Life Sciences

In living color: Brightly-colored bacteria could be used to 'grow' paints and coatings

20.02.2018 | Life Sciences

Observing and controlling ultrafast processes with attosecond resolution

20.02.2018 | Physics and Astronomy

VideoLinks
Science & Research
Overview of more VideoLinks >>>