Quasi-two-dimensional spin correlations in the triangular lattice bilayer spin glass LuCoGaO4

Article

关键词: SHORT-RANGE ORDER;    ANTIFERROMAGNET LUFEMGO4;    MAGNETIC-STRUCTURE;    MOSSBAUER;    CRYSTAL;    VISUALIZATION;    SOFTWARE;    BEHAVIOR;    YBFE2O4;    LUFE2O4;   

DOI  :  10.1103/PhysRevB.96.094414

来源: SCIE

【 摘 要 】

We present a single-crystal time-of-flight neutron scattering study of the static and dynamic spin correlations in LuCoGaO4, a quasi-two-dimensional dilute triangular lattice antiferromagnetic spin-glass material. This system is based on Co2+ ions that are randomly distributed on triangular bilayers within the YbFe2O4-type, hexagonal crystal structure. Antiferromagnetic short-range two-dimensional correlations at wave vectors Q = (1/3,1/3, L) develop within the bilayers at temperatures as high as |circle minus CW| similar to 100 K and extend over roughly five unit cells at temperatures below T-g = 19 K. These two-dimensional static correlations are observed as diffuse rods of neutron scattering intensity along c* and display a continuous spin freezing process in their energy dependence. Aside from exhibiting these typical spin-glass characteristics, this insulating material reveals a novel gapped magnetic resonant spin excitation at Delta E similar to 12 meV localized around Q = (1/3,1/3, L). The temperature dependence of the spin gap associated with this two-dimensional excitation correlates with the evolution of the static correlations into the spin-glass state ground state. We associate it with the effect of the staggered exchange field acting on the Seff = 1/2 Ising-like doublet of the Co2+ moments.

【 授权许可】

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