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】
Free