Experiments demonstrate unusual melting and recrystallization behavior in one-dimensional electron crystals

Mar 22, 2013
Credit: iStockphoto/Thinkstock

(Phys.org) —The melting of ice is a familiar process: the ice gradually loses its crystalline structure and becomes a featureless puddle of liquid. Normally, no amount of further heating will bring back the crystalline structure. Experiments by Hiroki Ikegami and co-workers at the Low Temperature Physics Laboratory in the RIKEN Advanced Science Institute have now shown that a one-dimensional 'Wigner' crystal on the surface of liquid helium can be made to repeatedly melt and recrystallize with rising electron density.

The researchers studied a one-dimensional system of electrons floating on the surface of using an intricate device designed to trap electrons in -sized channels. In these channels, the electrons adopt well-defined structures consisting of one or several chains with a few hundred electrons each. This arrangement provides an ideal setup for studying the behavior of such one-dimensional systems, explains Ikegami. "Generally, experiments involving regularly arranged chains are difficult because in many materials defects are inevitable. Our system is free from impurities and our sophisticated yields uniform channels to which the electrons are confined."

In their perfectly clean system, the researchers could control the number of electrons in each chain, and therefore the density of the one-dimensional crystals. They found that when they increased the in the channel, the melting temperature at which the chains lose their well-ordered structure initially increased, as expected. At higher densities, however, they discovered that the melting temperature decreased, only to increase and then decrease again. "This sort of 're-entrant' melting behavior has been predicted in computer simulations, but it was surprising for us that we could really observe it in a real experimental system," says Ikegami.

The team came up with a detailed model that explains the periodical modulation of the melting temperature as a function of density. In essence, the model suggests that at each change, the number of chains in the channel increases. In future research, the team plans to use their microchannel setup to perform quantum computations, in which the chains of electrons would be used to store and process information.

"Several schemes for quantum computation using electrons have been proposed," explains Ikegami. All of these schemes require single electrons to be confined to a small region—precisely the purpose for which the device developed by Ikegami and his team was made. "Our technique allows us to confine electrons in one direction, but more technical development is required before we can implement specific proposals."

Explore further: Watching the structure of glass under pressure

More information: Ikegami, H., Akimoto, H., Rees, D. G. and Kono, K. Evidence for reentrant melting in a quasi-one-dimensional Wigner crystal. Physical Review Letters 109, 236802 (2012). dx.doi.org/10.1103/PhysRevLett.109.236802

Related Stories

Nanoscale constrictions open up

Aug 17, 2012

If people bump into one another too often at a building’s entrance, the owner could opt to build a larger doorway. But physicists from the RIKEN Advanced Science Institute in Wako have shown that this ...

Bristol physicists break 150-year-old law

Jul 20, 2011

(PhysOrg.com) -- A violation of one of the oldest empirical laws of physics has been observed by scientists at the University of Bristol. Their experiments on purple bronze, a metal with unique one-dimensional ...

Materials scientists watch electrons 'melt'

Nov 22, 2011

(PhysOrg.com) -- When a skier rushes down a ski slope or a skater glides across an ice rink, a very thin melted layer of liquid water forms on the surface of the ice crystals, which allows for a smooth glide ...

Recommended for you

Watching the structure of glass under pressure

14 hours ago

Glass has many applications that call for different properties, such as resistance to thermal shock or to chemically harsh environments. Glassmakers commonly use additives such as boron oxide to tweak these ...

Inter-dependent networks stress test

17 hours ago

Energy production systems are good examples of complex systems. Their infrastructure equipment requires ancillary sub-systems structured like a network—including water for cooling, transport to supply fuel, and ICT systems ...

Explainer: How does our sun shine?

18 hours ago

What makes our sun shine has been a mystery for most of human history. Given our sun is a star and stars are suns, explaining the source of the sun's energy would help us understand why stars shine. ...

User comments : 0