Managing Quantum Effects through Material Imperfections

An international team led by Professor Dongchen Qi of the QUT School of Chemistry and Physics and Professor Xiao Renshaw Wang of Nanyang Technological University in Singapore has discovered how tiny imperfections and vibrations inside a promising quantum material can be used to control an unusual quantum effect, opening up new possibilities for smaller, faster, and more efficient energy-harvesting devices. The results were published in Newton.

Image Credit: Leo Matyushkin/Shutterstock.com

The international team set out to uncover the mechanism driving the nonlinear Hall effect (NLHE).

Unlike the classical Hall effect, this quantum counterpart can convert alternating electrical signals; such as those found in wireless transmissions or ambient energy sources, directly into usable direct current. In doing so, it removes the need for conventional diodes or other bulky components, offering a more streamlined approach to energy conversion.

The NLHE is a sophisticated quantum phenomenon in condensed matter physics where a voltage is generated perpendicular to an applied alternating current, even in the absence of a magnetic field. This effect allows us to convert alternating signals straight into direct current, which is what’s needed to power electronic devices. In principle, it means sensors or chips that could operate without batteries, drawing energy from their environment.

Dongchen Qi, Professor, School of Chemistry and Physics, Queensland University of Technology

The researchers examined bismuth telluride, a high-quality topological material recognized for its distinctive electronic properties, and found that the nonlinear Hall effect remains stable up to room temperature.

They also observed that temperature influences both the direction and magnitude of the generated voltage, highlighting its role in tuning the material’s electrical response.

At low temperatures, minor flaws in the material dominated the behavior. As the material warmed, natural vibrations in the crystal lattice took control, causing the electrical signal to reverse direction.

Once you understand what’s happening inside the material, you can design devices to take advantage of it. That’s when quantum effects stop being abstract and start becoming useful – supporting future applications ranging from self-powered sensors and wearable technology to ultra-fast components for next-generation wireless networks.

Dongchen Qi, Professor, School of Chemistry and Physics, Queensland University of Technology