All That Matters

Fridge magnets, and related magnets used in homes and offices, are made from the ceramic BaFe₁₂O₁₉, whose annual commercial production reaches 830,000 tons a year. Contrary to what their mundane use suggests, the physics of these magnets is rather unusual. They belong to a rare class of materials whose magnetism can be controlled with electric voltages and vice versa, which offers a new way of controlling magnetic fields in applications such as information storage (other than putting notes up on your fridge!).

Unfortunately, in most of these ceramics such effects are confined to low temperatures and have been mainly of interest to physicists only. Tsuyoshi Kimura and colleagues from Osaka University may now have changed this. They have discovered that in a close relative of fridge magnets, Sr₃Co₂Fe₂₄O₄₁, coupled interactions between magnetic and electric properties occur even at room temperature. “This demonstrates that such magnets can be used for other practical usages,” says Kimura. Their work is published online this week in Nature Materials.

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If you look at the image of an atom in a text book, it looks rather quiet and peaceful. There is a nucleus in the center made from a number of protons and neutrons. Around the nucleus the electrons typically are shown to orbit the core like planets around the sun.

Cover of the 5 August 2010 issue of Nature (c) nature publishing group

The reality, however, is far more complicated. First of all, the electrons don’t look like small planets, but are smeared out in complex shapes known as orbitals. The energy states of the different orbitals correspond to the electron shells in atomic physics. And secondly the electron motion is extremely fast, on the timescale of a femtosecond (fs), which is 10^-15 seconds. This is so short that even light can’t move very far in such a short time. Within a femtosecond it travels only about a third of a micrometer. So the question is, how is it possible to take a snapshot of such a fast motion? Well, one needs to use a camera that is even faster.

This ‘camera’ is a laser with attosecond resolution. An attosecond (as) is a thousand times faster than a femtosecond. In the present case, pulses of 150 as were used. These lasers are seriously fast. So fast that the light wave in the laser pulse completes only about one cycle. A bit like a tsunami wave that consists of only one big up and downwards motion of the water. Attosecond lasers were pioneered among others by Ferenc Krausz, with the clear aim of using them to venture into the intriguing realm of attosecond science. And it is his group that has now accomplished another major feat: the imaging of electron motions in the outer orbitals of krypton atoms. Their study appears in this week’s Nature, where it was also chosen for the cover.

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Looking at sheer numbers, science writing is in a boom, enabled by the relative ease of publishing on the internet. Just looking at condensed matter physics and related areas such as nanotechnology, there are wonderful blogs such as 2020 Science, Condensed Concepts, nanoscale views, Soft Machines, and Uncertain Principles. If you do not follow them already, I suggest you take a look.

(c) Intel

But despite all the exciting developments in the field, condensed matter physics is not as much in the limelight as say, the LHC or personal genomics. And this despite revolutionary techniques that have a profound impact on our daily life: the transistor, semiconductor lasers, computer hard drives, or the latest advances in nanotechnology, to name but a few.

A few weeks ago, Chad Orzel wrote about this problem in his blog, mentioning that comparatively few people write about the exciting discoveries in condensed matter physics. Doug Natelson took this further and identified a number of problems related to the perceived relevance and profundity of the field, as well as the issue of accessibility for a field whose scientific concepts are often difficult to relay to non-experts.

In my opinion these are of course all valid points, but not impossible to overcome. Of course, it can be a difficult topic to write about. But we need to get the message out more often, so that it sticks better. The problem is certainly not a lack of people in the field. Condensed matter physics researchers make up the majority of members of the American Physical Society. The large body of research they create certainly provides plenty of material to write about.

I have been pondering about the launch of a blog for a while, but constraints on my time have always put me off the idea. However, this recent discussion has finally convinced me that a blog in this area might be of benefit.

In comparison to writers such as Doug and Chad, who are respected university professors, I can offer a slightly different perspective, namely that of an editor of a scientific magazine with experience in research areas ranging from condensed matter physics to chemistry, nanotechnology, materials science and photonics. I frequently discuss current trends and opinions with researchers in these fields. By launching this blog, I hope to bring you some of the exciting stories in this field and hope to increase the interest in a research area that is so relevant to the technologies that we use in our daily life.