Researchers have successfully extended the quantum properties of a 3-atom-thin advanced material from extremely cold conditions to well above room temperature by combining it with the amino acid arginine. The international collaboration, published in Nature Chemistry, points toward potential applications including energy-efficient computer memory.
A team of investigators has managed to stabilize a delicate quantum state at temperatures up to about 135 degrees Fahrenheit. This is close to the highest heat ever measured in Death Valley, California.
Previously, the material required temperatures 135 degrees below zero Fahrenheit. This was close to the most frigid temperature ever recorded in Antarctica to exhibit its unusual behavior, according to findings from an international collaboration led by researchers at the UCLA College and the California NanoSystems Institute at UCLA.
How Arginine Locks Tantalum Disulfide Into Place
The base substance consists of stacked, 3-atom-thin sheets made from tantalum disulfide. In a typical metal, electrons move more or less randomly and are easily bumped off course when ambient heat causes small-scale vibrations.
However, this material can enter a specialized state known as the commensurate charge density wave, or CCDW. In this quantum state, electrons flow together in an orderly pattern that traces the internal structure of the material.
Getting that synchronized movement to survive warm environments required introducing arginine, a building block for proteins. The researchers constructed repeated vertical stacks featuring two layers of arginine sandwiched between single layers of tantalum disulfide, as detailed in research published in Nature Chemistry. When the team tested two other amino acids with the tantalum disulfide, neither produced CCDW behavior at room temperature.
The researchers found that the arginine molecule fits into the tantalum disulfide’s crystal matrix like a puzzle piece. The perfect fit of the amino acid’s size and how its electrons are distributed seem to explain its dramatic effect.
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From a Screening Accident to Rational Design
The discovery stemmed from an earlier screening project where scientists combined tantalum disulfide with more than 50 different carbon-based molecules to see which ones combine with advanced materials. The realization that arginine extended the temperature range for the commensurate charge density wave emerged as a happy accident during subsequent analysis.
To confirm the mechanics, the team used techniques measuring atomic structure, electrical flow, temperature changes, and vibrations, while computer simulations helped explain why the amino acid altered the material.
Xiangfeng Duan, a distinguished professor of chemistry and biochemistry who holds UCLA’s Raymond A. and Dorothy A. Wilson Endowed Chair, serves as the study’s corresponding author. Co-first authors include UCLA postdoctoral researchers Jingyuan Zhou and Boxuan Zhou, with theoretical analysis contributions led by USC engineering professor Zhenglu Li.
Pathways Toward Quantum Memory
The use of an amino acid represents a rare example. Inorganic materials chemists are employing molecular chemistry to modulate the electronic behavior of inorganic crystals, opening up design possibilities for advanced materials to include other molecules of life.
Future development of the tantalum disulfide and arginine combination could yield energy-efficient computer memory based entirely on quantum properties rather than the electrons that are the basis for traditional electronics.
Scientists might one day start with a targeted property like superconductivity and design or identify custom molecules to achieve it.