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

Abstract

Uranium compounds can manifest a wide range of fascinating many-body phenomena, and are often thought to be poised at a crossover between localized and itinerant regimes for 5f electrons. The antiferromagnetic dipnictide USb2 has been of recent interest due to the discovery of rich proximate phase diagrams and unusual quantum coherence phenomena. Here, linear-dichroic X-ray absorption and elastic neutron scattering are used to characterize electronic symmetries on uranium in USb2 and isostructural UBi2. Of these two materials, only USb2 is found to enable strong Hund's rule alignment of local magnetic degrees of freedom, and to undergo distinctive changes in local atomic multiplet symmetry across the magnetic phase transition. Theoretical analysis reveals that these and other anomalous properties of the material may be understood by attributing it as the first known high temperature realization of a singlet ground state magnet, in which magnetism occurs through a process that resembles exciton condensation.

References in corpus (8)

• Strong electronic correlations from Hund's coupling
• Nature of the 5f states in actinide metals
• Coherence-incoherence crossover in the normal state of iron-oxypnictides and importance of the Hund's rule coupling
• Orbital-assisted metal-insulator transition in VO${}_2$
• Spectroscopic determination of the atomic f-electron symmetry underlying hidden order in URu${}_2$Si${}_2$
• Direct bulk sensitive probe of 5f symmetry in URu2Si2
• The Tricritical Point of the f-electron Antiferromagnet USb2 Driven by High Magnetic Fields
• Charge transfer excitations in VUV and soft X-ray resonant scattering spectroscopies