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Perovskite Manipulated To Carry Both Electrical and Magnetic Polarization

Engineered properties could lead to low-power information storage and processing

2 min read
Perovskite Manipulated To Carry Both Electrical and Magnetic Polarization
Illustration: University of Liverpool

Researchers at the University of Liverpool in the UK have demonstrated the ability to manipulate a material so that it has both magnetic and electrical polarization, a feature that could lead to low-power electrical writing of information with non-destructive magnetic reading, and logic devices that can operate without charge current flow.

A fair amount of research has gone into exploiting this property of both electrical and magnetic polarization in bismuth ferrite, which has the rare property of possessing a permanent local magnetic field while always possessing an electric polarization that can be switched by applying an electric field.

However, in research published in the journal Science, the Liverpool team employed crystal chemistry to engineer specific atomic displacements in a layered perovskite to give it properties it did not previously possess. Perovskites are a class of crystals that have become all the rage, especially in the world of photovoltaics, because of their low cost, high charge-carrier mobility, and long diffusion lengths. In real world terms, this means that the electrons in perovskite-based photovoltaics can travel through thicker solar cells, which absorb more light and thereby generate more electricity than thinner cells.

In these most recent experiments, concern for perovskites’ attractive properties in photovoltaics were set aside so that the perovskite crystal could be engineered to have a novel set of properties.

“By designing in the required atomic-level changes using both computation and experiment together, we produced three properties (polarization, magnetization, magnetoelectricity) from a material that initially displayed none of them,” said Liverpool professor Matthew Rosseinsky, in a press release.

Rosseinsky added: “We were able to demonstrate that the magnetization and polarization are coupled by measuring the linear magnetoelectric coefficient, a key physical quantity for the integration of such materials in a device. This coupling arises because both properties are produced by the same single set atomic motions that we built in to the material.”

While these developments could potentially lead to applications for information storage, the researchers concede that a number of challenges still have to be overcome before making that step, including switching the polarization and making the material more electrically insulating.

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3 Ways 3D Chip Tech Is Upending Computing

AMD, Graphcore, and Intel show why the industry’s leading edge is going vertical

8 min read
Vertical
A stack of 3 images.  One of a chip, another is a group of chips and a single grey chip.
Intel; Graphcore; AMD
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A crop of high-performance processors is showing that the new direction for continuing Moore’s Law is all about up. Each generation of processor needs to perform better than the last, and, at its most basic, that means integrating more logic onto the silicon. But there are two problems: One is that our ability to shrink transistors and the logic and memory blocks they make up is slowing down. The other is that chips have reached their size limits. Photolithography tools can pattern only an area of about 850 square millimeters, which is about the size of a top-of-the-line Nvidia GPU.

For a few years now, developers of systems-on-chips have begun to break up their ever-larger designs into smaller chiplets and link them together inside the same package to effectively increase the silicon area, among other advantages. In CPUs, these links have mostly been so-called 2.5D, where the chiplets are set beside each other and connected using short, dense interconnects. Momentum for this type of integration will likely only grow now that most of the major manufacturers have agreed on a 2.5D chiplet-to-chiplet communications standard.

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