Tag Archives: Ella Maru Studio

Bringing a technique from astronomy down to the nanoscale

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A January 2, 2020 Columbia University news release on EurekAlert (also on phys.org but published Jan. 3, 2020) describes research that takes the inter-galactic down to the quantum level,

Researchers at Columbia University and University of California, San Diego, have introduced a novel “multi-messenger” approach to quantum physics that signifies a technological leap in how scientists can explore quantum materials.

The findings appear in a recent article published in Nature Materials, led by A. S. McLeod, postdoctoral researcher, Columbia Nano Initiative, with co-authors Dmitri Basov and A. J. Millis at Columbia and R.A. Averitt at UC San Diego.

“We have brought a technique from the inter-galactic scale down to the realm of the ultra-small,” said Basov, Higgins Professor of Physics and Director of the Energy Frontier Research Center at Columbia. Equipped with multi-modal nanoscience tools we can now routinely go places no one thought would be possible as recently as five years ago.”

The work was inspired by “multi-messenger” astrophysics, which emerged during the last decade as a revolutionary technique for the study of distant phenomena like black hole mergers. Simultaneous measurements from instruments, including infrared, optical, X-ray and gravitational-wave telescopes can, taken together, deliver a physical picture greater than the sum of their individual parts.

The search is on for new materials that can supplement the current reliance on electronic semiconductors. Control over material properties using light can offer improved functionality, speed, flexibility and energy efficiency for next-generation computing platforms.

Experimental papers on quantum materials have typically reported results obtained by using only one type of spectroscopy. The researchers have shown the power of using a combination of measurement techniques to simultaneously examine electrical and optical properties.

The researchers performed their experiment by focusing laser light onto the sharp tip of a needle probe coated with magnetic material. When thin films of metal oxide are subject to a unique strain, ultra-fast light pulses can trigger the material to switch into an unexplored phase of nanometer-scale domains, and the change is reversible.

By scanning the probe over the surface of their thin film sample, the researchers were able to trigger the change locally and simultaneously manipulate and record the electrical, magnetic and optical properties of these light-triggered domains with nanometer-scale precision.

The study reveals how unanticipated properties can emerge in long-studied quantum materials at ultra-small scales when scientists tune them by strain.

“It is relatively common to study these nano-phase materials with scanning probes. But this is the first time an optical nano-probe has been combined with simultaneous magnetic nano-imaging, and all at the very low temperatures where quantum materials show their merits,” McLeod said. “Now, investigation of quantum materials by multi-modal nanoscience offers a means to close the loop on programs to engineer them.”

The excitement is palpable.

Caption: The discovery of multi-messenger nanoprobes allows scientists to simultaneously probe multiple properties of quantum materials at nanometer-scale spatial resolutions. Credit: Ella Maru Studio

Here’s a link to and a citation for the paper,

Multi-messenger nanoprobes of hidden magnetism in a strained manganite by A. S. McLeod, Jingdi Zhang, M. Q. Gu, F. Jin, G. Zhang, K. W. Post, X. G. Zhao, A. J. Millis, W. B. Wu, J. M. Rondinelli, R. D. Averitt & D. N. Basov. Nature Materials (2019) doi:10.1038/s41563-019-0533-y Published: 16 December 2019

This paper is behind a paywall.

Bulletproof graphene

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A December 18, 2017 news item on Nanowerk announces research that demonstrates graphene can be harder than diamonds (Note: A link has been removed),

Imagine a material as flexible and lightweight as foil that becomes stiff and hard enough to stop a bullet on impact. In a newly published paper in Nature Nanotechnology (“Ultrahard carbon film from epitaxial two-layer graphene”), researchers across The City University of New York (CUNY) describe a process for creating diamene: flexible, layered sheets of graphene that temporarily become harder than diamond and impenetrable upon impact.

Scientists at the Advanced Science Research Center (ASRC) at the Graduate Center, CUNY, worked to theorize and test how two layers of graphene — each one-atom thick — could be made to transform into a diamond-like material upon impact at room temperature. The team also found the moment of conversion resulted in a sudden reduction of electric current, suggesting diamene could have interesting electronic and spintronic properties. The new findings will likely have applications in developing wear-resistant protective coatings and ultra-light bullet-proof films.

A December 18, 2017 CUNY news release, which originated the news item, provides a little more detail,

“This is the thinnest film with the stiffness and hardness of diamond ever created,” said Elisa Riedo, professor of physics at the ASRC and the project’s lead researcher. “Previously, when we tested graphite or a single atomic layer of graphene, we would apply pressure and feel a very soft film. But when the graphite film was exactly two-layers thick, all of a sudden we realized that the material under pressure was becoming extremely hard and as stiff, or stiffer, than bulk diamond.”

Angelo Bongiorno, associate professor of chemistry at CUNY College of Staten Island and part of the research team, developed the theory for creating diamene. He and his colleagues used atomistic computer simulations to model potential outcomes when pressurizing two honeycomb layers of graphene aligned in different configurations. Riedo and other team members then used an atomic force microscope to apply localized pressure to two-layer graphene on silicon carbide substrates and found perfect agreement with the calculations. Experiments and theory both show that this graphite-diamond transition does not occur for more than two layers or for a single graphene layer.

“Graphite and diamonds are both made entirely of carbon, but the atoms are arranged differently in each material, giving them distinct properties such as hardness, flexibility and electrical conduction,” Bongiorno said. “Our new technique allows us to manipulate graphite so that it can take on the beneficial properties of a diamond under specific conditions.”

The research team’s successful work opens up possibilities for investigating graphite-to-diamond phase transition in two-dimensional materials, according to the paper. Future research could explore methods for stabilizing the transition and allow for further applications for the resulting materials.

There’s an artist’s representation of a bullet’s impact on graphene,

By applying pressure at the nanoscale with an indenter to two layers of graphene, each one-atom thick, CUNY researchers transformed the honeycombed graphene into a diamond-like material at room temperature. Photo credit: Ella Maru Studio Courtesy: CUNY

Here’s a link to and a citation for the paper,

Ultrahard carbon film from epitaxial two-layer graphene by Yang Gao, Tengfei Cao, Filippo Cellini, Claire Berger, Walter A. de Heer, Erio Tosatti, Elisa Riedo, & Angelo Bongiorno. Nature Nanotechnology (2017) doi:10.1038/s41565-017-0023-9 Published online: 18 December 2017

This paper is behind a paywall.