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arXiv · 2610.36799

Stripe antiferromagnetic order and spin dynamics in the Shastry-Sutherland Ising compound Er2Be2GeO7

Donger Cheng·Otkur Omar·Wenbin Wei·Jan Peter Embs·Xiao Wang·Cheng Su·Hui Cheng·Zhengdong Fu·Xinzhi Liu·Wentao Jin·Ze Hu·Wei Luo·Liming Wang·Jiazheng Hao·Feiran Shen·Lunhua He·Shang Gao·Erxi Feng
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Abstract

In rare-earth compounds, the interplay between geometric frustration and unusual single-ion anisotropy caused by the crystal electric field often leads to exotic magnetic phases. Here, we investigate the magnetic properties of the rare-earth Shastry-Sutherland compound Er$_2$Be$_2$GeO$_7$ using bulk measurements and neutron scattering down to sub-Kelvin temperatures. A $k=(0,0,0)$ stripe-like antiferromagnetic order with locally tilted Er$^{3+}$ moments is revealed by time-of-flight neutron powder diffraction, accompanied with a $λ$-shape specific-heat anomaly at $T_N=0.84$ K. The temperature dependence of the magnetic peak intensity corresponding to the ordered moment of Er$^{3+}$ approximates to the two-dimensional Ising universality class. Thermal- and cold-neutron inelastic scattering experiments demonstrate that the strong Ising anisotropy originates from the local crystal electric field, and reveal gapped magnetic excitations with weak dispersion in the ordered state. Mean-field random-phase approximation with inequivalent nearest-neighbor couplings accounts well for the collective excitations, while classical Monte Carlo simulations yield the fractional $1/4$ and $1/2$ magnetization plateaus. Our work provides a comprehensive description of the spin correlations in Er$_2$Be$_2$GeO$_7$ with a particular focus on the classical origin of its fractional magnetization plateaus.

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Donger Cheng, Otkur Omar, Wenbin Wei, Jan Peter Embs, Xiao Wang, Cheng Su, Hui Cheng, Zhengdong Fu, Xinzhi Liu, Wentao Jin, Ze Hu, Wei Luo, Liming Wang, Jiazheng Hao, Feiran Shen, Lunhua He, Shang Gao, Erxi Feng. 2026-10-27. Stripe antiferromagnetic order and spin dynamics in the Shastry-Sutherland Ising compound Er2Be2GeO7. https://arxiv.org/abs/2610.36799

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