High temperature singlet-based magnetism from Hund's rule correlations

Area of Science:

• Condensed matter physics
• Materials science
• Quantum magnetism

Background:

• Uranium compounds exhibit complex many-body phenomena.
• 5f electrons in uranium materials are at a crossover between localized and itinerant regimes.
• Antiferromagnetic USb2 shows rich phase diagrams and quantum coherence.

Purpose of the Study:

• To characterize the electronic symmetries of uranium in USb2 and UBi2.
• To understand the unusual magnetic properties of USb2.
• To identify the underlying mechanism of magnetism in USb2.

Main Methods:

• Linear-dichroic X-ray absorption spectroscopy.
• Elastic neutron scattering.
• Theoretical analysis of electronic structure and magnetic properties.

Main Results:

• USb2 exhibits strong Hund's rule alignment of local magnetic moments.
• Distinct changes in local atomic multiplet symmetry occur across the magnetic phase transition in USb2.
• USb2 is identified as the first high-temperature realization of a singlet ground state magnet.

Conclusions:

• The magnetism in USb2 arises from a process resembling exciton condensation.
• USb2 presents a novel high-temperature singlet ground state magnetic system.
• These findings advance the understanding of exotic electronic states in uranium-based materials.