Amazing stuff!
"A new way to create ultra-thin layers of metals makes it possible for scientists to study a new and unusual class of 2D materials. Researchers in China used the technique to make layers of five different metals that were only a few angstroms thick, uncovering exotic physical properties. ...
The 6.3Å-thick bismuth sample is just two atoms deep and was stable for a whole year while the team tested its properties. The researchers noted that the bismuth sample shows strongly enhanced electrical conductivity, a notable field effect and a new and ‘prominent’ phonon mode. ..."
From the abstract:
"Two-dimensional (2D) metals are appealing for many emergent phenomena and have recently attracted research interests. Unlike the widely studied 2D van der Waals (vdW) layered materials, 2D metals are extremely challenging to achieve, because they are thermodynamically unstable.
Here we develop a vdW squeezing method to realize diverse 2D metals (including Bi, Ga, In, Sn and Pb) at the ångström thickness limit. The achieved 2D metals are stabilized from a complete encapsulation between two MoS2 monolayers and present non-bonded interfaces, enabling access to their intrinsic properties.
Transport and Raman measurements on monolayer Bi show excellent physical properties, for example, new phonon mode, enhanced electrical conductivity, notable field effect and large nonlinear Hall conductivity. Our work establishes an effective route for implementing 2D metals, alloys and other 2D non-vdW materials, potentially outlining a bright vision for a broad portfolio of emerging quantum, electronic and photonic devices."
Realization of 2D metals at the ångström thickness limit (no public access)
Atomic force microscopy image of a 2D bismuth sample consisting of the monolayer, bilayer and trilayer
The process of making the 2D metals involves squeezing them between sapphire anvils at high pressures
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