Chemistry is Getting Frustrated–That’s a Good Thing

Electrons in a metal want to move freely—that’s the basis for electrical conductivity. But if you restrict that movement, these particles, which generally don’t want anything to do with one another, will begin to act in unison. Such collective behavior can give rise to a number of enigmatic quantum phenomena, like superconductivity, charge density waves, and quantum spin liquids. 

How far electrons can roam is determined by how the different atoms in a material are arranged in the material: its crystal lattice symmetry. Columbia chemist Xavier Roy, whose lab specializes in creating custom crystals, wants to move beyond the limits of lattices. With the support of a $2 million Brown Investigator Award, Roy will design new ways to engineer what’s known as “frustration of electron motion” into real materials. 

Roy joins Columbia physicists Cory Dean and Tanya Zelevinsky in receiving the award from the Brown Institute for Basic Sciences at Caltech, which recognizes mid-career scientists pursuing curiosity-driven research in physics and chemistry. His award was announced on May 19, 2025. 

“My work combines physics and chemistry,” said Roy. “We pair the zoomed-out, lattice-level view of materials that physicists often take with the local bonding intuition that guides chemists. This project will combine both pictures to chemically synthesize frustrated materials and reveal their unique physical properties.”

Frustration, as studied so far, occurs when the geometric arrangement of atoms in a material prevents its electrons from settling into a configuration that satisfies all their preferred interactions, whether related to spin, charge, or motion. An electron can easily “hop” between two points if doing so lowers its energy. But imagine a triangle. In a triangular arrangement, the third corner introduces a conflict: the electron cannot simultaneously minimize its energy with respect to all neighbors. This creates a stand-off, leaving the electrons unable to settle into a stable configuration. Their motion becomes constrained—they are, in effect, frustrated, and may become collectively trapped.

However, real-world examples of frustration from lattice geometry remain relatively rare. Roy is looking beyond geometry and into the underlying chemistry of materials as a new route to engineer frustration in electronic systems.

Chemists think of materials in terms of their chemical bonds, which are determined by the space, called orbitals, that electrons can occupy around an atom. Those orbitals, which come in four basic shapes, can introduce frustration for electrons in ways not immediately apparent from the material’s lattice symmetry alone.

Roy’s starting point is a layered van der Waals material made of palladium, aluminum, and iodine, Pd₅AlI₂. Its clover-shaped d-orbitals form a checkerboard pattern that mimics what’s known as a Lieb lattice, a frustrated square-shaped structure that had only existed in theory. 

According to Roy, preliminary results with this frustrated material position it as a promising testbed for exploring quantum phases. The Brown Award will support his continued research using Pd₅AlI₂ and his efforts to identify atomic orbital-based design principles that could lead to the discovery of entirely new frustrated materials to explore. In the future, materials like these could open the door to new quantum technologies, from energy-efficient electronics to ultra-sensitive sensors and powerful quantum computers. By building unusual electronic behaviors directly into a material’s structure, Roy’s work could help make such technologies more stable, powerful, and easier to build.