The vector tomography method developed at MISTRAL beamline of the ALBA Synchrotron enables to visualize with nanometric resolution the orientation of the magnetization in magnetic singularities located in magnetic films or multilayers. After 10 years of research, it is reported the first observation of hyperbolic Bloch points, attractive entities for magnetic information transport.
About 70% of all the digitally stored data in the world are located in magnetic bits on disks that have to rotate to reach the location of movable reading sensors. This storage technology, thirty years old, consumes energy and dissipates heat at undesired levels. The search for more efficient methods has been, and still is, an active field of investigation.
Instead of movable parts as disks that require electrical motors, one aims to move the magnetic domains in magnetic ultra-thin films by applying electrical currents or other excitations reducing the operating powers by orders of magnitude. Within this general approach, known as spintronics, the magnetic domains and the walls that separate domains with opposite magnetization are very important actors.
The magnetic structure of the domain walls historically classified in Bloch and Neel types, includes singularities namely skyrmions, merons and Bloch points among others, that have only been observed in recent years. The structure of the magnetization in these singularities may confer them enough energetic stability to be considered as possible dynamic entities for spintronic-based magnetic memories.
As their sizes are nanometric and their magnetic conformation is in general complicated, state of the art microscopy methods are required to visualize them. At the MISTRAL beamline of the ALBA Synchrotron this topic has been investigated since already ten years and progressively the accuracy of the description of magnetic entities has been improved. The experimental method, known as vector magnetic tomography, allows to visualize with nanometric resolution the orientation of the magnetization in magnetic singularities located in magnetic films or multilayers. It is based on the angular dependence of the dichroic magnetic absorption (different X ray absorption for right and left handed circularly polarized photons).
Read more on ALBA website