Strong Neel Ordering and Luminescence Correlation in a Two‐Dimensional Antiferromagnet

Abstract

Magneto‐optical effect has been widely used in light modulation, optical sensing, and information storage. Recently discovered 2D van der Waals layered magnets are considered as promising platforms for investigating novel magneto‐optical phenomena and devices, due to the long‐range magnetic ordering down to atomically thin thickness, rich species, and tunable properties. However, majority 2D antiferromagnets suffer from low luminescence efficiency which hinders their magneto‐optical investigations and applications. This work uncovers strong light‐magnetic ordering interactions in 2D antiferromagnetic MnPS3 using a newly‐emerged near‐infrared photoluminescence (PL) mode far below its intrinsic bandgap. This ingap PL mode shows strong correlation with the Neel ordering and persists down to monolayer thickness. Combining the density‐functional theory (DFT), scanning transmission electron microscopy (STEM), and X‐ray photoelectron spectroscopy (XPS), this work illustrates the origin of the PL mode and its correlation with Neel ordering, which can be attributed to the oxygen ion‐mediated states. Moreover, the PL strength can be further tuned and enhanced using ultraviolet‐ozone (UVO) treatment. The studies offer an effective approach to investigate light‐magnetic ordering interactions in 2D antiferromagnetic semiconductors.

Optical markers of magnetic phase transition in CrSBr

“…The slope-temperature curve shows a linear region of 100 to 150 K. The linear fit can be used to extract the maximum intensity temperature of PL when the slope is zero, which is T = 110 ± 33 K. This value agrees well with the Néel transition temperature T N = 131 K of the bulk CrSBr. We also noticed that the PL intensity-temperature crossover is very broad, from 100 to 150 K. A similar correlation between PL intensity and Néel temperature in another antiferromagnetic van der Waals semiconductor MnPS 3 was found recently by Zhou et al 30…”

Photoluminescence and Raman Enhancement by Edge Plasmons in MnPS3

“…They were assigned to I 1 (spin up) and I 2 (spin down) oxygen ion-mediated states that were previously predicted by DFT calculations. 3 The energy of the PL 2 component corresponds to the previously experimentally observed spin-down I 2 state. 3 However, the spin-up I 1 state was not previously observed.…”

“…This thickness dependence is mainly due to the PL 2 component as shown in Figure h, in which the edge/center ratio of PL 1 stays constant as a function of thickness, while the corresponding PL 2 ratio shows a maximum at 185 nm. This result indicates plasmonic modification of the charge density in the edge areas …”

“…Manganese phosphosulfide (MnPS 3 ) is a promising 2D antiferromagnetic layered material for magneto-optical and spintronics applications with a wide band gap of ∼2.9 eV. , Recently, new oxygen ion-mediated states were discovered in MnPS 3 with near-infrared PL far below the intrinsic band gap that correlated with antiferromagnetic ordering . Unfortunately, this PL intensity significantly decreased at room temperature due to strong phonon–exciton coupling, which hinders applications.…”

Thickness-dependent excitonic properties of WSe2/FePS3 van der Waals heterostructures

“…This suggests the presence of a strong correlation between excitonic properties of WSe 2 /FePS 3 heterostructures and the antiferromagnetic ordering of FePS 3 . When T < T N , the PL intensity of heterostructures increases with increasing temperature because the thermal fluctuations will disturb the antiferromagnetic ordering induced by spin–spin interactions in FePS 3 , 43 which thus affects the charge transfer processes from FePS 3 to WSe 2 and then the PL of WSe 2 . When T > T N , FePS 3 becomes paramagnetic and it can be approximated with being a non-magnetic semiconductor, in which the electron–phonon interactions play a key role in affecting the charge transfer processes.…”