Tag: magnesium

Magnesium Protects Tantalum

Magnesium Protects Tantalum

UPTON, NY—Scientists at the U.S. Department of Energy’s (DOE) Brookhaven National Laboratory have discovered that adding a layer of magnesium improves the properties of tantalum, a superconducting material that shows great promise for building qubits, the basis of quantum computers. As described in a paper just published in the journal Advanced Materials, a thin layer of magnesium keeps tantalum from oxidizing, improves its purity, and raises the temperature at which it operates as a superconductor. All three may increase tantalum’s ability to hold onto quantum information in qubits.

This work builds on earlier studies in which a team from Brookhaven’s Center for Functional Nanomaterials (CFN), Brookhaven’s National Synchrotron Light Source II (NSLS-II), and Princeton University sought to understand the tantalizing characteristics of tantalum, and then worked with scientists in Brookhaven’s Condensed Matter Physics & Materials Science (CMPMS) Department and theorists at DOE’s Pacific Northwest National Laboratory (PNNL) to reveal details about how the material oxidizes.

Those studies showed why oxidation is an issue.

“When oxygen reacts with tantalum, it forms an amorphous insulating layer that saps tiny bits of energy from the current moving through the tantalum lattice. That energy loss disrupts quantum coherence—the material’s ability to hold onto quantum information in a coherent state,” explained CFN scientist Mingzhao Liu, a lead author on the earlier studies and the new work.

While the oxidation of tantalum is usually self-limiting—a key reason for its relatively long coherence time—the team wanted to explore strategies to further restrain oxidation to see if they could improve the material’s performance.

“The reason tantalum oxidizes is that you have to handle it in air and the oxygen in air will react with the surface,” Liu explained. “So, as chemists, can we do something to stop that process? One strategy is to find something to cover it up.”

All this work is being carried out as part of the Co-design Center for Quantum Advantage (C2QA), a Brookhaven-led national quantum information science research center. While ongoing studies explore different kinds of cover materials, the new paper describes a promising first approach: coating the tantalum with a thin layer of magnesium.

Read more on BNL website

Image: Chenyu Zhou, a research associate in the Center for Functional Nanomaterials (CFN) at Brookhaven National Laboratory and first author on the study, with Mingzhao Liu (CFN), Yimei Zhu (CMPMS), and Junsik Mun (CFN and CMPMSD), at the DynaCool Physical Property Measurement System (PPMS) in CFN. The team used this tool to make tantalum thin films with and without a protective magnesium layer so they could determine whether the magnesium coating would minimize tantalum oxidation.

Credit: Jessica Rotkiewicz/Brookhaven National Laboratory

Laura Heyderman elected Royal Society Fellow

Laura Heyderman elected Royal Society Fellow

Today, the announcement was made that Laura Heyderman, who leads the Mesoscopic Systems Group at PSI, has been elected Fellow of the Royal Society (FRS). Laura’s nomination recognises almost 30 years of research into magnetic materials and magnetism on the nanoscale, most notably, in the field of artificial spin ice.

Laura Heyderman is best known for her breakthroughs with nanomagnets – minute bar magnets that are a few hundreds of times smaller than the width of a human hair. Her research group, shared between Paul Scherrer Institute PSI and ETH Zurich where she became full professor in 2013, use these to create elaborate structures and devices. With the help of the large research infrastructures at PSI (X-rays, muons and neutrons) they then investigate the novel phenomena that they exhibit. The tiny magnetic systems they create can have a range of technological applications, such as for computation, communication, sensors or actuators.

Read more on the PSI website

Image: Laura Heyderman began working on magnetism as a PhD student investigating magnetic thin films in Paris in 1988. Today, she leads the Mesoscopic Systems Group, shared between PSI and ETH where she is a full professor.

Credit: ETH Zurich / Giulia Marthaler

Imaging Earth’s crust reveals natural secret for reducing carbon emissions

Imaging Earth’s crust reveals natural secret for reducing carbon emissions

Using the Canadian Light Source (CLS) at the University of Saskatchewan and its BMIT-ID beamline, he discovered much larger pores in samples from the Earth’s crust than predicted.

“I expected nanometer-sized pores, whereas I ended up finding pores up to 200 microns — so several orders of magnitudes larger,” said Pujatti, a scientist in the University of Calgary’s Department of Geoscience who recently defended his PhD. “This was very, very puzzling to me.”

Three-dimensional CLS imaging techniques allowed him to see the rocks’ internal structure. There, he found the pores in a mineral called olivine, which is made up largely of silica and magnesium.

As in other geologic systems, he thought the olivine would form new minerals — basically clays — as it dissolved “but I didn’t see that,” he said. “I could only see pores.”

“Finally, I realized the types of fluids that percolated through these rocks were too cold to lead to the formation of new minerals.” The ‘culprit’ was simply sea water.

“Classically, we always consider the oceanic crust as a sink for magnesium,” he said. “Instead, interactions between fluids and these olivine-rich rocks release magnesium.”

Read more on the Canadian Light Source website

Image: Simone Pujatti (right) and Benjamin Tutolo.