Clemson researchers tackle challenge in new quantum materials design

Developing new advanced materials for quantum information science is much like conducting an orchestra.

“When you go to a symphony and hear a good piece of music, it’s coherent. Everything flows together and it hits each note in the right spot. They come in at the right time. Why is the music attractive? Because when the conductor directs the piece, it is intentional and predictable in the progression and evolution of the notes and the message to be delivered,” said Thao Tran, an assistant professor in the Department of Chemistry at Clemson University.

Coherency is important in the development of quantum materials as well.

“In solid state quantum computing, you want to compute and transmit the information, and you want it to be intentional, predictable and controllable,” she said. 

Noncentrosymmetric triangular magnets offer a unique platform for realizing strong quantum fluctuations, said Xudong Huai, a fifth-year graduate student in Tran’s lab. Quantum fluctuations refer to the unpredictable behavior of particles at the quantum level. In certain materials, particularly those with specific geometric arrangements like triangular lattices, the fluctuations can be particularly strong.

“You have a large degree of freedom, a lot of options, in spin, orbital, symmetry and chemical bonding,” Huai said. “The question is how can you tune in the conditions that are just right — working together like a team and not fighting against each other — so you can realize quantum fluctuations that can potentially lead to the coherent quantum motion of the particle?”

Huai and two former Clemson students — Emmanuel Acheampong and Erich Delles — collaborated with scientists from Poland, the Philippines, Georgia Tech, the University of Houston, the University of Utah and two U.S. federal laboratories to develop a new noncentrosymmetric triangular-lattice magnet, CaMnTeO₆.

Huai said calcium, manganese, tellurium and oxygen were chosen based on their nuclear spins and stable isotopes. They also wanted the magnet’s structure to be geometrically frustrated, which means spins interact through competing exchange interactions that cannot be simultaneously satisfied.

“That contributes to the quantum dynamic,” Tran said. “There’s a sweet spot. If there’s not enough frustration, then we’re not going to realize that quantum fluctuation. But if there’s too much frustration, it can lead to disorder.”

The new model material displays competing magnetic interactions and features nonlinear optical responses with the capability of generating coherent photons.

“This is a design strategy. At this point in material research, we want to be more intentional with the research. Can we rationally design something meaningful and then build in the functionality rather than do something just based on luck?” Tran said. “This research gives us a map. We have a better idea of where to start and where to go from here.”

The research could lead to new solid-state quantum materials that would advance technologies such as spin-based electronics, communications, resilient climate change models and state-of-the-art medical imaging and drug design.

Detailed findings can be found in the paper titled “Noncentrosymmetric Triangular Magnet CaMnTeO₆: Strong Quantum Fluctuations and Role of s⁰ versus s² Electronic States in Competing Exchange Interactions” published in the journal Advanced Materials.

The work at Clemson as supported by the Arnold and Mabel Beckman Foundation through a 2023 Beckman Young Investigators Award to Thao Tran.