Researchers Uncover Link Between Magnetic Ordering and Jahn-Teller Effect

A team of researchers from Waseda University has made a significant breakthrough in understanding the relationship between magnetic ordering and the Jahn-Teller effect. Their study, published in the journal Physical Review Letters on October 29, 2025, reveals that magnetic ordering can induce the Jahn-Teller effect in certain spinel-type compounds, a finding that could have implications for quantum information technology.

The Jahn-Teller effect, first described in 1937 by physicists Hermann Jahn and Edward Teller, explains how crystals with degenerate electronic orbitals can lower their energy by distorting their structure. This distortion stabilizes particular orbitals occupied by electrons, but the involvement of magnetism in this process has rarely been observed. Typically, magnetic ordering occurs at much lower temperatures than the distortions caused by the Jahn-Teller effect, complicating the connection between these phenomena.

Led by Professor Takuro Katsufuji from the Department of Physics at Waseda University, the research team, which includes Master’s students Minato Nakano and Taichi Kobayashi, focused on spinel-type compounds with the formula AV2O4. Their investigations centered on Co1−xFexV2O4, where they observed that the Jahn-Teller distortion occurs simultaneously with magnetic ordering.

Significant Findings in Spinel-Type Compounds

In their experiments, the researchers discovered that in FeV2O4, the Fe2+ ions exhibit a Jahn-Teller distortion that transforms the crystal structure from cubic to tetragonal symmetry. In contrast, CoV2O4, which lacks orbital degeneracy in Co2+, does not show similar behavior. By studying single crystals of Co1−xFexV2O4 with varying levels of iron, the team noted that the Jahn-Teller structural transition aligns with the temperature at which magnetic ordering initiates. As the amount of iron decreases, the intensity of the Jahn-Teller distortion also diminishes.

This discovery establishes that magnetic ordering can indeed trigger Jahn-Teller distortions, facilitated by spin-orbit coupling, which refers to the interaction between an electron’s spin and its orbital angular momentum. The research indicates that the doubly degenerate e g states of the d orbitals in Fe2+ ions can be influenced by magnetic fields below one tesla, suggesting potential applications in the field of quantum information.

Potential Applications and Future Research

While controlling or measuring the state of a single Fe2+ ion remains a challenge, the findings suggest a pathway forward. By reducing the concentration of Fe2+ ions in the crystal, it might become feasible to control and read the state of individual ions with magnetic fields. This advancement could pave the way for innovative applications in quantum information technologies.

Professor Katsufuji highlighted the theoretical advancements that could arise from their research. He noted, “By substituting the V in FeV2O4 with a non-magnetic ion instead of replacing Fe with Co, we can suppress the ordering of Fe spins. This is expected to create a new state of matter where orbital-spin coupling exists but both are simultaneously frustrated. Such a state, where these two degrees of freedom are entangled and fluctuate together, is unprecedented.”

These findings not only contribute to the fundamental understanding of magnetic and orbital interactions but also hold promise for the development of next-generation quantum information systems. As research continues, further exploration into the relationship between magnetism and structural distortions may yield even more exciting discoveries in this field.