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This study leverages nitrogen-vacancy center magnetometry to resolve the Néel transition in individual LaCrO$_3$ microcrystals, bypassing the ensemble averaging limitations of traditional techniques like SQUID or neutron diffraction. By imaging stray magnetic fields at the single-particle level, researchers have identified micron-scale pinned antiferromagnetic domains and localized impurities that dictate temperature-dependent switching behavior. These findings establish NV centers as a critical tool for correlating particle morphology with magnetic ordering in rare-earth orthochromites, advancing materials science for quantum sensing applications.
Single-particle detection of the N\'eel transition in LaCrO$_3$ microcrystals via widefield nitrogen-vacancy center magnetic imaging
arXiv:2609.38529v1 Announce Type: cross Abstract: Rare-earth orthochromites exhibit rich, chemically tunable magnetic behavior, making them attractive for temperature sensing and temperature-dependent switching applications. Realizing this potential requires understanding how synthesis conditions and particle morphology influence the underlying Cr$^{3+}$ magnetic ordering. Orthochromite magnetism has traditionally been characterized by ensemble techniques such as neutron diffraction and SQUID magnetometry, which report only averaged magnetic properties and cannot access particle-level information. Here we use widefield nitrogen-vacancy (NV) magnetometry to image the stray magnetic fields of individual LaCrO$_3$ microcrystals produced via molten salt synthesis, resolving the antiferromagnetic N\'eel transition in single particles. Of the 18 particles measured between 278 and 298 K, five show a clear onset of magnetization near the ensemble N\'eel temperature, four show no measurable magnetic signal, and nine display temperature-independent signatures consistent with localized magnetic impurities undetected by ensemble measurements. Below the N\'eel temperature, particle magnetization remains fixed under a rotating in-plane field, consistent with canted antiferromagnetic ordering rather than paramagnetism, while repeated thermal cycling shows that the magnetic field pattern varies between cooldowns with certain features recurring at the same locations, consistent with micron-scale structurally pinned antiferromagnetic domains in which the sign of the weak ferromagnetic moment is set independently each time they pass through the N\'eel transition. These results establish single-particle NV magnetometry as a sensitive probe of magnetic ordering and domain structure in individual microcrystals, a key step toward correlating individual particle morphology and defect structure with magnetic ordering in orthochromites.
Abstract:Rare-earth orthochromites exhibit rich, chemically tunable magnetic behavior, making them attractive for temperature sensing and temperature-dependent switching applications. Realizing this potential requires understanding how synthesis conditions and particle morphology influence the underlying Cr$^{3+}$ magnetic ordering. Orthochromite magnetism has traditionally been characterized by ensemble techniques such as neutron diffraction and SQUID magnetometry, which report only averaged magnetic properties and cannot access particle-level information. Here we use widefield nitrogen-vacancy (NV) magnetometry to image the stray magnetic fields of individual LaCrO$_3$ microcrystals produced via molten salt synthesis, resolving the antiferromagnetic Néel transition in single particles. Of the 18 particles measured between 278 and 298 K, five show a clear onset of magnetization near the ensemble Néel temperature, four show no measurable magnetic signal, and nine display temperature-independent signatures consistent with localized magnetic impurities undetected by ensemble measurements. Below the Néel temperature, particle magnetization remains fixed under a rotating in-plane field, consistent with canted antiferromagnetic ordering rather than paramagnetism, while repeated thermal cycling shows that the magnetic field pattern varies between cooldowns with certain features recurring at the same locations, consistent with micron-scale structurally pinned antiferromagnetic domains in which the sign of the weak ferromagnetic moment is set independently each time they pass through the Néel transition. These results establish single-particle NV magnetometry as a sensitive probe of magnetic ordering and domain structure in individual microcrystals, a key step toward correlating individual particle morphology and defect structure with magnetic ordering in orthochromites.
Materials Science (cond-mat.mtrl-sci); Mesoscale and Nanoscale Physics (cond-mat.mes-hall); Quantum Physics (quant-ph)
arXiv:2609.38529 [cond-mat.mtrl-sci]
(or arXiv:2609.38529v1 [cond-mat.mtrl-sci] for this version)
https://doi.org/10.48550/arXiv.2609.38529 Focus to learn more arXiv-issued DOI via DataCite (pending registration)
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