Key Points:
- MIT researchers developed a precise method for tuning quantum materials by adjusting the Fermi level using high-energy hydrogen ions.
- The technique allows for milli-electron volt accuracy, significantly reducing the time required for tuning from weeks to minutes.
- The method is versatile, applicable to various inorganic materials, and could enhance properties like superconductivity and thermoelectric efficiency.
- The development could advance quantum computing by optimizing the electronic properties of quantum materials.
A team led by Mingda Li, an associate professor in MIT’s Department of Nuclear Science and Engineering (NSE), has developed a groundbreaking method for fine-tuning quantum materials, potentially paving the way for advancements in superconductivity, thermoelectric efficiency, and quantum computing. The technique, detailed in a recent open-access paper in Applied Physics Reviews, focuses on adjusting the Fermi level, which determines the electronic properties of quantum materials.
Quantum materials, governed by principles of quantum mechanics such as correlation and entanglement, exhibit exotic behaviors like superconductivity—the ability to conduct electricity without resistance. The materials must be precisely tuned to harness these behaviors, akin to fine-tuning a race car for optimal performance.
Li’s team has demonstrated a new way to achieve this precision using Weyl semimetals, a type of topological material known for its unique electronic structures called Weyl nodes. These nodes, resembling vortices, bestow the material with exceptional electrical properties that remain stable even when the material is disturbed.
The researchers’ method involves manipulating the Fermi level, the highest energy level occupied by electrons in a material. Using MIT’s two-stage “Tandem” ion accelerator, the team bombarded a tantalum phosphide (TaP) Weyl semimetal crystal with high-energy hydrogen ions. This process, known as doping, allowed them to add or subtract electrons to the material, fine-tuning the Fermi level with unprecedented accuracy—down to milli-electron volts (thousandths of an electron volt).
To ensure precision, the team developed a theoretical model to predict the exact number of hydrogen ions needed to adjust the Fermi level. This model streamlines the tuning process, significantly reducing the time required to achieve the desired electron configuration from weeks to minutes.
Although demonstrated on Weyl semimetals, this method is versatile and can be applied to other inorganic bulk materials and thin films. The ability to precisely control the Fermi level opens up new possibilities for enhancing the properties of quantum materials, including increasing the critical temperature for superconductivity and improving the efficiency of thermoelectric materials. The technique also holds promise for advancing quantum computing by optimizing the electronic characteristics of quantum materials.
Thomas Zac Ward, a senior scientist at Oak Ridge National Laboratory, praised the work as a significant milestone that could drive the development of new quantum information and microelectronics device architectures.
