A research team led by the University of Exeter has recently made a pivotal breakthrough in the all-optical switching of magnetization that demonstrates the potential to deliver nanoscale magnetic storage devices grounded exclusively on transition metals like iron, cobalt, or nickel.
A Phys.org report specified that the search for the delivery of ultra-fast, energy-efficient magnetic recording could be one step closer to fruition because of the pioneering study on "all-optical switching of magnetization."
As the capacity and electricity consumption of data centers rise exponentially, there is a demanding economic and societal need to search for more energy-efficient approaches to information storage.
Such a demand has stimulated extensive study initiative into new physical mechanisms for regulation of magnetization within magnetic thin films, for example, all-optical switching.
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Importance of Magnetic Recording
The several applications of magnetic recording use different media types, in general. Since every application has different "linear density, mechanical stresses, and pricing tradeoffs," ScienceDirect specified in a report, the ideal solutions vary substantially.
Since the signal largeness falls off exponentially with the head's distance from the media, enhancement in areal density has been made by reducing the media's thickness, not to mention reducing the head's fly height.
The second choice is only applicable to a hard disk since the head is in contact already, with the flexible disk and tape, Ultra Glass Coatings specified in a similar report.
In general, the magnetic medium comprises a constant magnetic layer atop a nonmagnetic substrate. Meanwhile, the substrate is a Mylar film or polyester for flexible disks and tape.
The substrate is painted with the magnetic particles' coating; gamma ferric oxide is usually combined in a binding solution.
Meanwhile, for tap, the particles' orientation is frequently regulated during the coating process by applying a strong magnetic field.
All-Optical Switching
Essentially, the all-optical switching of magnetization enables magnetic bits to be written purely by optical later pulses minus any requirement of an external magnetic field.
Previous research on all-optical switching of magnetization has nearly exclusively concentrated on rare-earth-based materials like gadolinium and terbium, limiting both the device's scalability and tenability.
From the technological applications' viewpoint, so-called "the rare-earth free synthetic ferrimagnets" used in this study are highly desirable because of the low cost and somewhat abundance of the constituent materials, as well as the incomparable tenability.
Results of the study, published in Nano Letters, have shown that the all-optical switching is driven by a spin-polarized current that's flowing between the two equivalent magnetic configurations with the antiparallel alignment of the "Ni3Pt and Co ferromagnetic layer."
Such switching can be attained independently of the light polarization, not to mention over a broad range of temperatures.
Key Ingredient
According to the study's first author, Maciej Dabrowski, from the University of Exeter, their findings demonstrate that the main ingredient for "helicity independent all-optical switching in rare-earth free synthetic ferrimagnet, is to have a par of unique metal layers.
By using Ni3Pt and Co layers, the first author explained that they were able to develop an imbalance of spin-polarized current for a trillionth of a second, following laser extinction, which eventually results in the magnetization switching.
Related information about all-optical control is shown on YoutubeINSTICC's YouTube video below:
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