Field-induced partial disorder in a Shastry-Sutherland lattice.

Marshall, Madalynn; Billingsley, Brianna R; Bai, Xiaojian; Ma, Qianli; Kong, Tai; Cao, Huibo · Nat Commun · 2023

basic_science · Level V

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Abstract

A 2-Q antiferromagnetic order of the ferromagnetic dimers was found below T<sub>N</sub> = 2.9 K in the Shastry-Sutherland lattice BaNd<sub>2</sub>ZnS<sub>5</sub> by single crystal neutron diffraction. The magnetic order can be understood by the orthogonal arrangement of local Ising Nd spins, identified by polarized neutrons. A field was applied along [1 -1 0] to probe the observed metamagnetic transition in the magnetization measurement. The field decouples two magnetic sublattices corresponding to the propagation vectors q<sub>1</sub> = (½, ½, 0) and q<sub>2</sub> = (-½, ½, 0), respectively. Each sublattice shows a "stripe" order with a Néel-type arrangement in each single layer. The "stripe" order with q<sub>1</sub> remains nearly intact up to 6 T, while the other one with q<sub>2</sub> is suppressed at a critical field H<sub>c</sub> ~1.7 T, indicating a partial disorder. The H<sub>c</sub> varies with temperature and is manifested in the H-T phase diagram constructed by measuring the magnetization in BaNd<sub>2</sub>ZnS<sub>5</sub>.