Revealed: 3D magnetic configuration of ferrimagnetic multilayers with competing interactions

Researchers from the Physics Department of the Universidad de Oviedo, CINN-CSIC and HZB, in collaboration with ALBA, have explored the magnetic configuration of ferrimagnetic structures often employed to build modern spintronic devices and magnetic recording media. At the MISTRAL beamline of ALBA, using vector magnetic tomography, a magnetic trilayer fabricated at Oviedo was characterized. These findings will permit to generate precise physical models describing the magnetic behaviour of this type of systems and control and exploit them for the design of spintronics and magnetic storage devices.

 Modern spintronic devices and magnetic recording media often consist of complex magnetic structures. These structures are designed by precisely adjusting magnetic interactions as exchange, anisotropies and magnetostatics to achieve specific characteristics.

A collaboration between researchers from the Physics Department of the Universidad de Oviedo, the Centro de Investigación en Nanomateriales y Nanotecnología (Oviedo), the Helmholtz Zentrum Berlin für Materialien und Energie (Berlin) and the ALBA Synchrotron have investigated a combination of ferrimagnetic structures, often employed to build this type of devices. 

At the MISTRAL beamline of ALBA, a dichroic vector magnetic tomography of the device was performed and it revealed details of complex magnetisation configurations of the sample. The importance of synchrotron light lies in the fact that this information is currently impossible to evidence with other techniques when studying magnetic thin films.

The ability to characterize the configuration of the magnetisation in complex structures with competing magnetic interactions will permit to generate precise physical models describing the magnetic behaviour of these systems. Thus, experts will be able to control and exploit them for the design of spintronics and magnetic storage devices.

Read more on the ALBA website

Image: Magnetisation obtained from the magnetic tomography data at the MISTRAL beamline.

Unusual electronic properties taking shape

In a recent study, an international team led by researchers from The Pennsylvania State University in the US investigated the one-dimensional (1D) material tantalum selenide iodide (TaSe4 )2I. Its electronic properties had been theoretically predicted but not observed experimentally before the study conducted at the Bloch beamline. Evaporating iodine atoms turn out to drive unforeseen electronic changes.

Materials with unusual electronic properties such as charge density waves or topological states push the understanding of the fundamentals of quantum matter. They are also exciting candidates for the next generations of energy-efficient electronic and spintronic devices.

In the present study, the researchers found that the electronic properties of (TaSe4 )2I were different from the theoretical prediction. The band structure of a material can loosely be compared to a map of the material’s electronic properties. (TaSe4 )2I has something called Dirac bands, which is often found in this type of materials. The prediction said that the Dirac bands would split due to Weyl physics, which is not the case. The bands split with temperature, and the driver behind it is iodine atoms evaporating from the material’s surface.

Read more on the MAX IV website

Image: Surface charge induced Dirac band splitting in 1D material (TaSe4 )2I