Field-induced partial disorder in a Shastry-Sutherland lattice

Marshall, Milton V.; Billingsley, Brianna R.; Bai, Xiaojian; Ma, Qianli; Kong, Tai; Cao, Huibo

doi:10.1038/s41467-023-39409-1

Cited by 8 publications

(1 citation statement)

References 58 publications

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“…The local susceptibility method with polarized neutron diffraction (PND) is based on the crystal structure and can reveal the orientation of the gtensor. The data on Er 3 Mg 2 Sb 3 O 14 by PND have been used to distinguish the true solution at the High Flux Isotope Reactor's DEMAND (HB-3A), similarly to the previously reported work (Marshall et al, 2023).…”

Section: Analysis Of the Crystal Field Parameters Of The Lowsymmetry ...mentioning

confidence: 91%

CrysFieldExplorer: rapid optimization of the crystal field Hamiltonian

Ma,

Bai,

Feng

et al. 2023

J Appl Cryst

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A new approach to the fast optimization of crystal electric field (CEF) parameters to fit experimental data is presented. This approach is implemented in a lightweight Python-based program, CrysFieldExplorer. The main novelty of the method is the development of a unique loss function, referred to as the spectrum characteristic loss (L Spectrum), which is based on the characteristic polynomial of the Hamiltonian matrix. Particle swarm optimization and a covariance matrix adaptation evolution strategy are used to find the minimum of the total loss function. It is demonstrated that CrysFieldExplorer can perform direct fitting of CEF parameters to any experimental data such as a neutron spectrum, susceptibility or magnetization measurements etc. CrysFieldExplorer can handle a large number of non-zero CEF parameters and reveal multiple local and global minimum solutions. Crystal field theory, the loss function, and the implementation and limitations of the program are discussed within the context of two examples.

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Section: Analysis Of the Crystal Field Parameters Of The Lowsymmetry ...mentioning

confidence: 91%

CrysFieldExplorer: rapid optimization of the crystal field Hamiltonian

Ma,

Bai,

Feng

et al. 2023

J Appl Cryst

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Noncollinear polar magnet Fe2(SeO3)3(H2O)3 with inequivalent Fe3+ sites

Oyeka,

Huai,

Marshall

et al. 2024

APL Materials

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The emergence of novel magnetic states becomes more likely when the inversion symmetry of the crystal field, relative to the center between two spins, is broken. We propose that placing magnetic spins in inequivalent sites in a polar lattice can promote a realization of nontrivial magnetic states and associated magnetic properties. To test our hypothesis, we study Fe2(SeO3)(H2O)3 as a model system that displays two distinct Fe(1) and Fe(2) magnetic sites in a polar structure (R3c space group). At low fields μ0H≤ 0.06 T, the material undergoes an antiferromagnetic ordering with TN1 = 77 K and a second transition at TN2≈ 4 K. At μ0H≥ 0.06 T and 74 K ≤T≤ 76 K, a positive entropy change of ∼0.12 mJ mol−1 K−1 can be associated with a metamagnetic transition to possibly nontrivial spin states. At zero field, Fe(1) is nearly fully ordered at T≈ 25 K, while Fe(2) features magnetic frustration down to T = 4 K. The magnetic ground state, a result corroborated by single-crystal neutron diffraction and 57Fe Mössbauer spectroscopy, is a noncollinear antiparallel arrangement of ferrimagnetic Fe(1)–Fe(2) dimers along the c-axis. The results demonstrate that placing distinct magnetic sites in a polar crystal lattice can enable a new pathway to modifying spin, orbital, and lattice degrees of freedom for unconventional magnetism.

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