“Strange Metal” Ytterbium Gets Even Stranger When Hit With Gamma Rays

Although no one is entirely sure why, the effect of high-energy photons produces changes in ytterbium's electrical charge.

When a quantum physicist describes a phenomenon as "weird," you can be sure that it is truly acting in an unusual way. Individuals who are at ease with superposition and "spooky action at a distance" have very high standards for what they consider to be strange. However, some substances have been given the moniker "weird metals" because their electrical conductivity differs from that of more well-known metals and is still poorly understood. The most recent illustration of this peculiarity, which stands out to scientists more than others, is a radiation absorption peak that has two peaks as opposed to the typical one.

Ytterbium has one of the strangest conductivities of all naturally occurring elements, as well as one of the most unlikely-sounding names. Although it is more prevalent in the Earth's crust than roughly half of the sub-Uranic elements, it is not especially widespread.

The peculiar conductivity of ytterbium has been studied by a Japanese-American team, and they describe their findings in a recent article.

Its fascination to Dr Yashar Komijani of the University of Cincinnati is that, when it conducts electricity, ytterbium doesn't act like known conductors like copper or aluminum. In a statement, Kominjani said: "In a metal, you have a sea of electrons flowing in the backdrop on a lattice of ions. But quantum physics causes a wonderful event to happen. You can disregard the atoms' lattice's complexities. They act as though they are in a void instead.

Ytterbium is more conductive when it's frigid than what science should predict. The hunt for high-temperature superconducting materials may benefit from this, but it also raises an oddity that Komijani and his co-authors are hoping to explain.

The writers examined the reaction of ß-YbAlB4, an alloy of ytterbium, aluminum, and boron, to gamma rays under various pressure and temperature conditions. This is paradoxical in a small way because ytterbium's primary use is as a source of gamma rays.

Although each radioactive disintegration process generates photons with a distinct energy, gamma rays are typically generated through this process. The team used the gamma rays released when protons collided with walls to conduct Mössbauer spectroscopy, a technique that can identify extremely minute changes in the chemical surroundings of nuclei, to generate gamma rays on demand.

The alloy changed from "strange metal" to a "Fermi liquid," the common condition of most elements, when the temps were maintained very low.

The writers observed that the absorption spectrum's double point was caused by charge variations. According to their analysis, this spectrum represents a single nuclear transition that has been influenced by neighboring electronic valence variations.

The timing of the charge changes, which happen every billionth of a second, affects the measurements. This is extremely sluggish by quantum norms, which the team traces to vibrations in the lattice.

The authors speculate that their findings might indicate a transition between what would be regarded as Yb2+ and Yb3+ ionic states in conventional physics but is more complicated in a quantum world, though they acknowledge they cannot be certain of this.

The double peak, according to the writers, may not be specific to ytterbium but rather a distinguishing characteristic of all strange metals that can be used to both identify and describe them.

A sample containing ytterbium was discovered close to the Swedish town of Ytterby, which gave the element its peculiar moniker. Despite being categorized as a rare Earth, it is more prevalent than most of its fellow members, including its periodic table companions lutetium and thulium, at 0.3 parts per million in the Earth's surface.

The study is published in Science