Scientists reveal how a novel ceramic achieves directional conduction

April 19, 2006

An international team led by University College London scientists at the London Centre for Nanotechnology has unravelled the properties of a novel ceramic material that could help pave the way for new designs of electronic devices and applications.

Working with researchers from the Swiss Federal Institute of Technology (ETH), Zurich, the University of Tokyo and Lucent Technologies, USA, they reveal in a Letter to Nature that the complex material, which is an oxide of manganese, functions as a self-assembled or 'natural' layered integrated circuit. By conducting electricity only in certain directions, it opens up the possibility of constructing thin metal layers, or racetracks, insulated from other layers only a few atoms away.

Currently, the race for increasingly small and more powerful devices has relied on two-dimensional integrated circuits, where functional elements such as transistors are engineered via planar patterning of the electrical properties of a semiconductor. Packing more functionalities into tiny electronic devices has until now been achieved by reducing the lateral size of each component, but a new realm of opportunity opens with the ability of building three-dimensional structures.

Professor Gabriel Aeppli, Director of the London Centre for Nanotechnology and co-author of the study, explains: "There is an issue of how you deal with leakage between layers when you pack circuits into three dimensions. Our work with the Tokyo-Lucent groups shows that you can have many layers with little or no leakage between them. This is because we're not dealing with ordinary electrons, but with larger objects, consisting of electrons bound to magnetic and other disturbances of the atomic fabric of the material, which can't travel across the barriers between layers."

The flow of electricity in modern electronic devices relies on the fact that electrons move readily in certain solids, such as metals like copper, and are blocked from moving in insulators such as quartz. In ordinary solids, electrons move similarly in all three dimensions, therefore if a material is metallic along one direction, it will be metallic in all directions. The ceramic – a manganese oxide alloy with the chemical formula La1.6Sr1.4Mn2O7 – has fascinated scientists for a decade due to the extraordinary sensitivity of its electrical properties to magnets placed near it. Most interesting was the discovery by the University of Tokyo group that even quite small magnets can switch electrical currents in the same way in this ceramic as in much more expensive, individually fabricated electronic devices of the type being tested for advanced magnetic data storage.

Using one of the classic tools of nanotechnology, the scanning tunnelling microscope, Dr Henrik Rønnow (ETH) and Dr Christoph Renner (LCN and UCL) swept a tiny metallic tip with sub-atomic accuracy over the surface of the ceramic to sense its topographic and electronic properties at spatial resolution of less than the diameter of a single atom. The data showed that this ceramic behaves like a perfect metal along the planes parallel to the surface and like an insulator along the direction perpendicular to the surface.

The results also revealed the first snap-shot of a possible culprit for this unusual electronic behaviour. In conventional solids, charge is carried by simple electrons, but in such ceramics, it is shuttled around by more complex objects, known as polarons, which consist of electrons bound to a magnetic disturbance as well as local displacements of atoms away from their ordinary positions.

Source: University College London

Explore further: Powerful ceramic fuel cells could enable in-home production of electricity from natural gas

Related Stories

New material releases stored heat under weak pressure

July 14, 2015

Researchers at the University of Tokyo have discovered a new type of material which stores heat energy for a prolonged period, which they have termed a "heat storage ceramic." This new material can be used as heat storage ...

Polymer mold makes perfect silicon nanostructures

July 3, 2015

Using molds to shape things is as old as humanity. In the Bronze Age, the copper-tin alloy was melted and cast into weapons in ceramic molds. Today, injection and extrusion molding shape hot liquids into everything from car ...

Recommended for you

How bees naturally vaccinate their babies

July 31, 2015

When it comes to vaccinating their babies, bees don't have a choice—they naturally immunize their offspring against specific diseases found in their environments. And now for the first time, scientists have discovered how ...

A cataclysmic event of a certain age

July 27, 2015

At the end of the Pleistocene period, approximately 12,800 years ago—give or take a few centuries—a cosmic impact triggered an abrupt cooling episode that earth scientists refer to as the Younger Dryas.

New blow for 'supersymmetry' physics theory

July 27, 2015

In a new blow for the futuristic "supersymmetry" theory of the universe's basic anatomy, experts reported fresh evidence Monday of subatomic activity consistent with the mainstream Standard Model of particle physics.

Dense star clusters shown to be binary black hole factories

July 29, 2015

The coalescence of two black holes—a very violent and exotic event—is one of the most sought-after observations of modern astronomy. But, as these mergers emit no light of any kind, finding such elusive events has been ...

0 comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.