Illustrative models of collinear ferromagnetism, antiferromagnetism, and altermagnetism in crystal-structure real space and nonrelativistic electronic-structure momentum space. (Credit: Libor Šmejkal et al., Phys. Rev. X, 2022)

Altermagnetism In Manganese Telluride And Others: The Future Of Spintronics?

August 1, 2024 by Maya Posch 5 Comments

Magnetic materials are typically divided into ferromagnetic and antiferromagnetic types, depending on their magnetic moments (electron spins), resulting in either macroscopic (net) magnetism or not. Altermagnetism is however a recently experimentally confirmed third type that as the name suggests alternates effectively between these two states, demonstrating a splitting of the spin energy levels (spin-split band structure). Like antiferromagnets, altermagnets possess a net zero magnetic state due to alternating electron spin, but they differ in that the electronic band structure are not Kramers degenerate, which is the feature that can be tested to confirm altermagnetism. This is the crux of the February 2024 research paper in Nature by [J. Krempaský] and colleagues.

Specifically they were looking for the antiferromagnetic-like vanishing magnetization and ferromagnetic-like strong lifted Kramers spin degeneracy (LKSD) in manganese telluride (MnTe) samples, using photoemission spectroscopy in the UV and soft X-ray spectra. A similar confirmation in RuO2 samples was published in Science Advances by [Olena Fedchenko] and colleagues.

What this discovery and confirmation of altermagnetism means has been covered previously in a range of papers ever since altermagnetism was first proposed in 2019 by [Tomas Jungwirth] et al.. A 2022 paper published in Physical Review X by [Libor Šmejkal] and colleagues details a range of potential applications (section IV), which includes spintronics. Specific applications here include things like memory storage (e.g. GMR), where both ferromagnetic and antiferromagnetics have limitations that altermagnetism could overcome.

Naturally, as a fairly new discovery there is a lot of fundamental research and development left to be done, but there is a good chance that within the near future we will see altermagnetism begin to make a difference in daily life, simply due to how much of a fundamental shift this entails within our fundamental understanding of magnetics.

Heading image: Illustrative models of collinear ferromagnetism, antiferromagnetism, and altermagnetism in crystal-structure real space and nonrelativistic electronic-structure momentum space. (Credit: Libor Šmejkal et al., Phys. Rev. X, 2022)

Spin Your Own Passive Cooling Fibres

July 31, 2024 by Jenny List 4 Comments

When the temperature climbs, it’s an eternal problem: how to stay cool. An exciting field of materials science lies in radiative cooling materials, things which reflect so much incoming heat that they can cool down from their own radiation rather than heating up in the sun. It’s something [NightHawkInLight] has been working on over a series, and he’s dropped a very long video we’ve placed below. It’s ostensibly about spinning radiative cooling fibers, but in fact provides a huge quantity of background as well as a bonus explanation of cotton candy machines.

These materials achieve their reflectivity by creating a surface full of microscopic bubbles. It’s the same process that makes snow so white and reflective, and in this case it’s achieved by dissolving a polymer in a mixture of two solvents. The lower boiling point solvent evaporates first leaving the polymer full of microscopic bubbles of the higher boiling point solvent, and once these evaporate they leave behind the tiny voids. In the video he’s using PLA, and we see him experimenting with different solvents and lubricants to achieve the desired result. The cotton candy machine comes in trying to create fibers by melting solid samples, something which doesn’t work as well as it could so instead he draws them by hand with a small rake.

When he tests his mat of fibers in bright sunlight the effect is almost magical if we didn’t already know the mechanism, they cool down by a few degrees compared to ambient temperature and the surrounding control materials. This is a fascinating material, and we hope we’ll see more experimenters working with it. You won’t be surprised to hear we’ve featured his work before.

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Printed Portable Computer Inspired By The Classics

July 28, 2024 by Tom Nardi 3 Comments

These days, laptop computers are all more or less the same, at least externally. Some are thicker than others, they might come in different colors, or with a 360° hinge that lets you flip the screen around the back and use it as a tablet, but overall they’ve all got the same shape and proportions. The industry, and indeed the users, eventually agreed on the best way to make a computer portable and are now fully committed to it.

But that wasn’t always the case. In the 1980s there were a number of laptops from the likes of Toshiba, Tandy, and even IBM that took a slightly different approach to the clamshell design. These computers featured ultra-wide displays with a hinge located closer to the center of the computer, giving the machine a distinctive “trunk” in the back. It’s these classic machines that clearly inspired [Michael Mayer] to design the Portable Pi 84.

[Michael] says that the 3D printed enclosure was largely designed around the 40% ortholinear keyboard, which itself is based on the Happy-Keyboard from [Luis Alegría]. The rest apparently just fell into place, such as the fact that the 1600 x 600 Waveshare 9.3 inch display happens to be almost the perfect size to cover the keyboard below it.

Compared to many of the other custom computer builds we’ve covered, the rear compartment of the Portable Pi 84 provides ample free space for the various system components. That includes the Raspberry Pi 4 that runs the show, a UPS “hat” that powers the system via a pair of 21700 batteries, and even a set of amplified speakers. It looks like there’s still plenty of room in the back for additional gear, such as an RTL-SDR or perhaps even a cartridge slot.

A particularly nice feature of this build are the inset panels on the rear of the machine, which allow for the various ports and connectors to be reconfigured by the user without having to re-print the entire case — one could imagine a replacement panel that features a connector for an external WiFi antenna, for example. We also like the use of heat-set inserts throughout the case, which will not only make the build sturdier, but means the case can be opened and closed regularly without fear of stripping out the screw holes.

So is this a computer or a cyberdeck? It’s hard to say. We tend to think that a proper deck needs to have a more unique physical layout, and technically this form factor was actually fairly popular at one point. But whatever you want to call builds like this, we’re stoked to see them become more common and better documented. Long live the truly personal computer.

Retro Inspired Cyberdeck Scrolls Around Cyberspace

July 25, 2024 by Tom Nardi 24 Comments

It’s difficult to nail down exactly what counts as a “real” cyberdeck in this brave new era of bespoke computing. But at the minimum, most in the community would agree that a proper deck should have a non-traditional form factor, and be designed to meet the unique needs of the builder. If you’re looking for a fantastic example of both concepts, check out the Cyberdore 2064 from [Tommi L].

At first glance the 3D printed enclosure of the Cyberdore looks a bit like a Speak & Spell, but it’s really more of an amalgamation of everything that made 1980s computers so unique. You’ve got the vents, the chunky switches, the undersized display, and of course, the handle. The case might have been extruded in 2024, but it’s doing a fantastic impression of a piece of tech from 40 years ago.

One of the key external features of the Cyberdore 2064 is the side-mounted rotary encoder that allows for smoothly scrolling through online feeds (such as your favorite hardware hacking site) or long documents. The cheap and easy to work with KY-040 encoder has been converted to a USB input device by way of a Pi Pico, and has been paired with an over-sized 3D printed knob that really makes this build stand out — not only visually, but in terms of usability. These cyberdeck builds often rely on touch screens for input, but we always appreciate a physical interface.

Under the hood you’ve got a Raspberry Pi Zero and an 18650 cell to keep the whole thing running while on the go. Though the Zero is certainly showing its age compared to the more modern variants of the Pi, for a device like this, raw computing power isn’t really the driving concern. A mechanical keyboard usually rounds out these cyberdeck builds, but in this case, [Tommi] went with a fairly common Rii 518BT portable board that’s been skillfully integrated into the front of the Cyberdore.

All of the STL files necessary to print out your own Cyberdore 2064 are available on Printables, and while [Tommi] didn’t exactly provide build instructions, the write-up provides plenty of information to get you started.

So is it just us, or does looking at Cyberdore 2064 make you think it’s time for another Hackaday Cyberdeck Challenge?

Pnut: A Self-Compiling C Transpiler Targeting Human-Readable POSIX Shell

July 25, 2024 by Maya Posch 16 Comments

Shell scripting is one of those skills that are absolutely invaluable on especially UNIX and BSD-based systems like the BSDs, the two zillion Linux distributions as well as MacOS. Yet not every shell is the same, and not everybody can be bothered to learn the differences between the sh, bash, ksh, zsh, dash, fish and other shells, which can make a project like Pnut seem rather tempting. Rather than dealing with shell scripting directly, the user writes their code in the Lingua Franca of computing, AKA C, which is then transpiled into a shell script that should run in any POSIX-compliant shell.

The transpiler can be used both online via the main Pnut website, as well as locally using the (BSD 2-clause) open source code on GitHub. Here the main limitations are also listed, which mostly concern the C constructs that do not map nicely to a POSIX shell. These are: no support for floating point numbers and unsigned integers, no goto and switch nor taking the address of a variable with &. These and preprocessor-related limitations and issues are largely to be expected, as especially POSIX shells are hardly direct replacements for full-blown C code.

As a self-professed research project, Pnut seems like an interesting project, although if you are writing shell scripts for anything important, you probably just want to buckle down and learn the ins and outs of POSIX shell scripting and beyond. Although it’s a bit of a learning curve, we’d be remiss if we said that it’s not totally worth it, if only because it makes overall shell usage even beyond scripting so much better.

Keep Your Lungs Clean And Happy With A DIY Supplied-Air Respirator

July 9, 2024 by Dan Maloney 13 Comments

The smell of resin SLA printing is like the weather — everybody complains about it, but nobody does anything about it. At least until now, as [Aris Alder] tackles the problem with an affordable DIY supplied-air respirator.

Now, we know what you’re thinking, anything as critical as breathing is probably best left to the professionals. While we agree in principle, most solutions from reputable companies would cost multiple thousands of dollars to accomplish, making it hard to justify for a home gamer who just doesn’t want to breathe in nasty volatile organic compounds. [Aris] starts the video below with a careful examination of the different available respirator options, concluding that a supplied air respirator (SAR) is the way to go.

His homebrew version consists of an affordable, commercially available plastic hood with a built-in visor. Rather than an expensive oil-free compressor to supply the needed airflow, he sourced a low-cost inline duct fan and placed it outside the work zone to pull in fresh air. Connecting the two is low-cost polyethylene tubing and a couple of 3D printed adapters. This has the advantage of being very lightweight and less likely to yank the hood off your head, and can be replaced in a few seconds when it inevitably punctures.

Another vital part of the kit is a pulse oximeter, which [Aris] uses to make sure he’s getting enough oxygen. His O₂ saturation actually goes up from his baseline when the hood is on and powered up, which bodes well for the system. Every time we pick up the welding torch or angle grinder we wish for something like this, so it might just be time to build one.

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Halfway Between Inspiration And Engineering

July 6, 2024 by Elliot Williams 7 Comments

We see a lot of hacks where the path to success is pretty obvious, if maybe strewn with all sorts of complications, land-mines, and time-sinks. Then we get other hacks that are just totally out-of-the-box. Maybe the work itself isn’t so impressive, or even “correct” by engineering standards, but the inner idea that’s so crazy it just might work shines through.

This week, for instance, we saw an adaptive backlight LED TV modification that no engineer would ever design. Whether it was just the easiest way out, or used up parts on hand, [Mousa] cracked the problem of assigning brightnesses to the LED backlights by taking a tiny screen, playing the same movie on it, pointing it at an array of light sensors, and driving the LEDs inside his big TV off of that. No image processing, no computation, just light hitting LDRs. It’s mad, and it involves many, many wires, but it gets the job done.

Similarly, we saw an answer to the wet-3D-filament problem that’s as simple as it could possibly be: basically a tube with heated, dry air running through it that the filament must pass through on it’s way to the hot end. We’ve seen plenty of engineered solutions to damp filament, ranging from an ounce of prevention in the form of various desiccant storage options, to a pound of cure – putting the spools in the oven to bake out. We’re sure that drying filament inline isn’t the right way to do it, but we’re glad to see it work. The idea is there when you need it.

Not that there’s anything wrong with the engineering mindset. Quite the contrary: most often taking things one reasonable step at a time, quantifying up all the unknowns, and thinking through the path of least resistance gets you to the finish line of your project faster. But we still have to admire the off-the-wall hacks, where the way that makes the most sense isn’t always the most beautiful way to go. It’s a good week on Hackaday when we get both types of projects in even doses.