'Exotic' material is like a switch when super thin

April 18, 2014 by Anne Ju
An artist’s rendering of the thickness-driven, metal-insulator transition in sub-nanometer films of a lanthanum nickelate. Nickel atoms are shown in gold, oxygen atoms in white, and lanthanum atoms in red, and metallicity is achieved in going from two to three atomic layers. Credit: Haofei Wei

(Phys.org) —Ever-shrinking electronic devices could get down to atomic dimensions with the help of transition metal oxides, a class of materials that seems to have it all: superconductivity, magnetoresistance and other exotic properties. These possibilities have scientists excited to understand everything about these materials, and to find new ways to control their properties at the most fundamental levels.

Researchers from Cornell and Brookhaven National Laboratory have shown how to switch a particular oxide, a lanthanum nickelate (LaNiO3), from a metal to an insulator by making the material less than a nanometer thick.

The team, which published its findings in the April issue of Nature Nanotechnology, includes lead researcher Kyle Shen, associate professor of physics; first author Phil King, a recent Kavli postdoctoral fellow at Cornell now on the faculty at the University of St. Andrews; Darrell Schlom, the Herbert Fisk Johnson Professor of Industrial Chemistry; and co-authors Haofei Wei, Yuefeng Nie, Masaki Uchida, Carolina Adamo, and Shabo Zhu (Cornell), and Xi He and Ivan Božović (Brookhaven National Laboratory).

Using an extremely precise growth technique called molecular-beam epitaxy (MBE), King synthesized atomically thin samples of the lanthanum nickelate and discovered that the material changes abruptly from a metal to an insulator when its thickness is reduced to below 1 nanometer. When that threshold is crossed, its conductivity – the ability for electrons to flow through the material – switches off like a light, a characteristic that could prove useful in nanoscale switches or transistors, Shen said.

Using a one-of-a-kind system at Cornell, which integrates MBE film growth with a technique called angle-resolved photoemission spectroscopy (ARPES), King and colleagues mapped out how the motions and interactions of the electrons in the material changed across this threshold, varying the thickness of their oxide films atom by atom. They discovered that when the films were less than 3 nickel atoms thick, the electrons formed an unusual nanoscale order, akin to a checkerboard.

The results demonstrate the ability to control the electronic properties of exotic at the nanometer scale, as well as revealing the striking cooperative interactions that govern the behavior of the electrons in these ultrathin materials. Their discovery paves the way for making advanced new from oxides.

Explore further: Elusive metal discovered

More information: Atomic-scale control of competing electronic phases in ultrathin LaNiO3, Nature Nanotechnology (2014) DOI: 10.1038/nnano.2014.59

Related Stories

Elusive metal discovered

August 22, 2012

Carnegie scientists are the first to discover the conditions under which nickel oxide can turn into an electricity-conducting metal. Nickel oxide is one of the first compounds to be studied for its electronic properties, ...

Interfaces are key in metal oxide superlattices

September 5, 2012

(Phys.org)—Materials called transition metal oxides have physicists intrigued by their potentially useful properties—from magnetoresistance (the reason a hard drive can write memory) to superconductivity.

Scalable CVD process for making 2-D molybdenum diselenide

April 8, 2014

(Phys.org) —Nanoengineering researchers at Rice University and Nanyang Technological University in Singapore have unveiled a potentially scalable method for making one-atom-thick layers of molybdenum diselenide—a highly ...

Recommended for you

Physicists develop new technique to fathom 'smart' materials

November 26, 2015

Physicists from the FOM Foundation and Leiden University have found a way to better understand the properties of manmade 'smart' materials. Their method reveals how stacked layers in such a material work together to bring ...

Mathematicians identify limits to heat flow at the nanoscale

November 24, 2015

How much heat can two bodies exchange without touching? For over a century, scientists have been able to answer this question for virtually any pair of objects in the macroscopic world, from the rate at which a campfire can ...

New sensor sends electronic signal when estrogen is detected

November 24, 2015

Estrogen is a tiny molecule, but it can have big effects on humans and other animals. Estrogen is one of the main hormones that regulates the female reproductive system - it can be monitored to track human fertility and is ...


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.