Neutrons Explore the Quantum Nature of Magnetically Frustrated Systems

Neutron scattering and heat capacity techniques were used to investigate two frustrated magnets with similar structure, but different sized spins (S).The research team, led by McMaster University, found the molybdate pyrochlore oxide material, Lu2Mo2O7 (S=1) undergoes a transition to a spin glass ground state, while the oxynitride Lu2Mo2O5N2 (S=1/2) possesses a quantum spin liquid ground state. The smaller spin of the oxynitride is subjected to larger quantum fluctuations that favor a quantum spin liquid state. The preparation of oxynitride samples makes it possible to study magnetic frustration for different spin magnitudes without changing the magnetic lattice. Inelastic neutron scattering conducted at the Cold Neutron Chopper Spectrometer (CNCS) instrument at the Spallation Neutron Source of the Oak Ridge National Laboratory was used to probe the length and energy scales of spin fluctuations.

L. Clark, G. J. Nilsen, E. Kermarrec, G. Ehlers, K. S. Knight, A. Harrison, J. P. Attfield and B. D. Gaulin. “From Spin Glass to Quantum Spin Liquid Ground States in Molybdate Pyrochlores.” Phys. Rev. Lett. 113 (2014): 117201. http://journals.aps.org/prl/abstract/10.1103/PhysRevLett.113.117201