Coexistence of antiferromagnetism and ferrimagnetism in adjacent honeycomb layers

D. Szaller; L. Prodan; K. Geirhos; V. Felea; Y. Skourski; D. Gorbunov; T. Förster; T. Helm; T. Nomura; A. Miyata; S. Zherlitsyn; J. Wosnitza; A. A. Tsirlin; V. Tsurkan; I. Kézsmárki

arXiv · 2202.04700

Coexistence of antiferromagnetism and ferrimagnetism in adjacent honeycomb layers

D. Szaller·L. Prodan·K. Geirhos·V. Felea·Y. Skourski·D. Gorbunov·T. Förster·T. Helm·T. Nomura·A. Miyata·S. Zherlitsyn·J. Wosnitza·A. A. Tsirlin·V. Tsurkan·I. Kézsmárki

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Abstract

Antiferromagnetic and ferro/ferrimagnetic orders are typically exclusive in nature, thus, their co-existence in atomic-scale proximity is expected only in heterostructures. Breaking this paradigm and broadening the range of unconventional magnetic states, we report here on an atomic-scale hybrid spin state, which is stabilized in three-dimensional crystals of the polar antiferromagnet Co$_2$Mo$_3$O$_8$ by magnetic fields applied perpendicular to the \emph{Co} honeycomb layers and possesses a spontaneous in-plane ferromagnetic moment. Our microscopic spin model, capturing the observed field dependence of the longitudinal and transverse magnetization as well as the magnetoelectric/elastic properties, reveals that this novel spin state is composed of an alternating stacking of antiferromagnetic and ferrimagnetic honeycomb layers. The strong intra-layer and the weak inter-layer exchange couplings together with competing anisotropies at octahedral and tetrahedral \emph{Co} sites are identified as the key ingredients to stabilize antiferromagnetic and ferrimagnetic layers in such a close proximity. We show that the proper balance of magnetic interactions can extend the stability range of this hybrid phase down to zero magnetic field. The possibility to realize a layer-by-layer stacking of such distinct spin orders via suitable combinations of microscopic interactions opens a new dimension towards the nanoscale engineering of magnetic states.

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D. Szaller, L. Prodan, K. Geirhos, V. Felea, Y. Skourski, D. Gorbunov, T. Förster, T. Helm, T. Nomura, A. Miyata, S. Zherlitsyn, J. Wosnitza, A. A. Tsirlin, V. Tsurkan, I. Kézsmárki. 2022-02-09. Coexistence of antiferromagnetism and ferrimagnetism in adjacent honeycomb layers. https://arxiv.org/abs/2202.04700

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