TY - JOUR
T1 - Bilayer Square Lattice Tb2SrAl2O7with Structural Z8Vortices and Magnetic Frustration
AU - Xu, Xianghan
AU - Huang, Fei Ting
AU - Admasu, Alemayehu S.
AU - Kim, Jaewook
AU - Wang, Kefeng
AU - Feng, Erxi
AU - Cao, Huibo
AU - Cheong, Sang Wook
N1 - Publisher Copyright:
© 2022 American Chemical Society.
PY - 2022/2/8
Y1 - 2022/2/8
N2 - The bilayer perovskites' family A3B2O7 holds rich structural complexity. When magnetism freedom is added in, great opportunities appear for new physics. Magnetic Tb ions in Tb2SrAl2O7 are known to crystallize in a bilayer square lattice. The results of our comprehensive neutron, X-ray diffraction, and transmission electron microscopy (TEM) experiments reveal a crystallographic P42/mnm symmetry accompanied with room-temperature topological type-II Z8 vortex domains, whose density is controllable by cooling rates, as described by the Kibble-Zurek mechanism. The DC magnetic susceptibility without long-range order down to 1.8 K suggests frustrated magnetism, while a spin freezing <2.5 K is observed in the AC susceptibility, which is likely due to the antisite disorder and another possible cause of no long-range ordering. Strong temperature evolution of magnetic anisotropy indicates an interplay of low-lying crystal electric field levels and anisotropic exchange interactions. Our results suggest that Tb2SrAl2O7 is a promising candidate of magnetic frustration in a bilayer square lattice, and this system can be a new playground for exploring exotic magnetic states in bilayer square lattices, topological magnetic edge states at coherent crystallographic domain walls, and multifunctional applications.
AB - The bilayer perovskites' family A3B2O7 holds rich structural complexity. When magnetism freedom is added in, great opportunities appear for new physics. Magnetic Tb ions in Tb2SrAl2O7 are known to crystallize in a bilayer square lattice. The results of our comprehensive neutron, X-ray diffraction, and transmission electron microscopy (TEM) experiments reveal a crystallographic P42/mnm symmetry accompanied with room-temperature topological type-II Z8 vortex domains, whose density is controllable by cooling rates, as described by the Kibble-Zurek mechanism. The DC magnetic susceptibility without long-range order down to 1.8 K suggests frustrated magnetism, while a spin freezing <2.5 K is observed in the AC susceptibility, which is likely due to the antisite disorder and another possible cause of no long-range ordering. Strong temperature evolution of magnetic anisotropy indicates an interplay of low-lying crystal electric field levels and anisotropic exchange interactions. Our results suggest that Tb2SrAl2O7 is a promising candidate of magnetic frustration in a bilayer square lattice, and this system can be a new playground for exploring exotic magnetic states in bilayer square lattices, topological magnetic edge states at coherent crystallographic domain walls, and multifunctional applications.
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U2 - 10.1021/acs.chemmater.1c03771
DO - 10.1021/acs.chemmater.1c03771
M3 - Article
AN - SCOPUS:85123588838
SN - 0897-4756
VL - 34
SP - 1225
EP - 1234
JO - Chemistry of Materials
JF - Chemistry of Materials
IS - 3
ER -