# Charge transfer and asymmetric coupling of MoSe2 valleys to the magnetic
order of CrSBr

C. Serati de Brito  Physics Department, Federal University of São Carlos, São
Carlos, SP, 13565-905, Brazil  P. E. Faria Junior  Institute of Theoretical
Physics, University of Regensburg, 93040 Regensburg, Germany  T. S. Ghiasi
Kavli Institute of Nanoscience, Delft University of Technology, Lorentzweg 1,
2628 CJ Delft, The Netherlands  J. Ingla-Aynés  Kavli Institute of
Nanoscience, Delft University of Technology, Lorentzweg 1, 2628 CJ Delft, The
Netherlands  C. R. Rabahi  Physics Department, Federal University of São
Carlos, São Carlos, SP, 13565-905, Brazil  C. Cavalini  Physics Department,
Federal University of São Carlos, São Carlos, SP, 13565-905, Brazil  F.
Dirnberger  Institute of Applied Physics and Würzburg-Dresden Cluster of
Excellence ct.qmat, Technische Universität Dresden, Germany  S. Mañas-Valero
Kavli Institute of Nanoscience, Delft University of Technology, Lorentzweg 1,
2628 CJ Delft, The Netherlands  K. Watanabe  Research Center for Materials
Nanoarchitectonics, National Institute for Materials Science, 1-1 Namiki,
Tsukuba 305-0044, Japan  T. Taniguchi  Research Center for Materials
Nanoarchitectonics, National Institute for Materials Science, 1-1 Namiki,
Tsukuba 305-0044, Japan  K. Zollner  Institute of Theoretical Physics,
University of Regensburg, 93040 Regensburg, Germany  J. Fabian  Institute of
Theoretical Physics, University of Regensburg, 93040 Regensburg, Germany  C.
Schüller  Institut für Experimentelle und Angewandte Physik, Universität
Regensburg, D-93040 Regensburg, Germany  H. S. J. van der Zant  Kavli
Institute of Nanoscience, Delft University of Technology, Lorentzweg 1, 2628
CJ Delft, The Netherlands  Y. Galvão Gobato<EMAIL_ADDRESS>Physics
Department, Federal University of São Carlos, São Carlos, SP, 13565-905,
Brazil

###### Abstract

Van der Waals (vdW) heterostructures composed of two-dimensional (2D)
transition metal dichalcogenides (TMD) and vdW magnetic materials offer an
intriguing platform to functionalize valley and excitonic properties in non-
magnetic TMDs. Here, we report magneto-photoluminescence (PL) investigations
of monolayer (ML) MoSe2 on the layered A-type antiferromagnetic (AFM)
semiconductor CrSBr under different magnetic field orientations. Our results
reveal a clear influence of the CrSBr magnetic order on the optical properties
of MoSe2, such as an anomalous linear-polarization dependence, changes of the
exciton/trion energies, a magnetic-field dependence of the PL intensities, and
a valley $g$-factor with signatures of an asymmetric magnetic proximity
interaction. Furthermore, first principles calculations suggest that
MoSe2/CrSBr forms a broken-gap (type-III) band alignment, facilitating charge
transfer processes. The work establishes that antiferromagnetic-nonmagnetic
interfaces can be used to control the valley and excitonic properties of TMDs,
relevant for the development of opto-spintronics devices.

###### keywords:

Transition Metal Dichalcogenides, two-dimensional magnets, van der Waals
Heterostructures, Proximity Effects, Magneto-Optics.

Institut für Experimentelle und Angewandte Physik, Universität Regensburg,
D-93040 Regensburg, Germany Instituto de Ciencia Molecular (ICMol),
Universitat de València, Catedrático José Beltrán 2, Paterna 46980, Spain

## 1

Recently, van der Waals (vdW) magnetic materials have attracted increasing
attention because of their unique magnetic properties and possible
applications in spintronics1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13. Several
studies were performed in heterostructures using magnetic materials and
monolayer TMDs14, 15, 16, 3, 17, 2, 1, 18, 19, 20, 21, 22. These
heterostructures employ magnetic proximity effects to modify the physical
properties of the ML TMD adjacent to the magnetic material and therefore offer
new opportunities for engineering magnetic heterostructures18. Actually,
recent studies evidenced an enhanced valley splitting of WSe2 and WS2
monolayers on the ferromagnetic (FM) material EuS23, 24, a giant zero-field
valley splitting of MoSe2/CrBr325, asymmetric magnetic proximity interactions
in MoSe2/CrBr316, and an anomalous temperature dependence of the MoSe2/MnPSe3
excitonic peak below the Néel temperature ($T_{N}$) 3. Furthermore, magnetic
proximity effects have led to spin-dependent charge transfer and concomitant
circularly polarized PL in hybrid devices based on both CrI317, 2 and CrBr31.
However, most previous studies in magnetic vdW heterointerfaces involved vdW
ferromagnetic materials1, 2, 3, 4, 5, 6. AFM materials have a variety of spin
orderings with distinct magnetic symmetry groups which could result in unique
magnetic properties and therefore there are interesting ways to control their
functionalities by choosing appropriate AFM materials3.

In this work, we investigate the impact of the CrSBr antiferromagnetic
substrate on the exciton and valley properties of ML MoSe2. We have performed
micro-PL measurements under a magnetic field along each of the three
crystallographic axes of CrSBr. In general, our findings show that the exciton
and valley properties of ML TMDs can be engineered by the interplay of
magnetic proximity, efficient charge transfer effects, exciton/trion-magnon
coupling and dielectric anomalies of 2D antiferromagnetic materials.

The layered magnetic material CrSBr is a vdW direct gap semiconductor with
A-type AFM and Neél temperature of 132 K in its bulk form.26, 27, 28, 29, 30,
31, 32, 33, 34. In addition, CrSBr presents another phase transition around
the temperature of $T=40$ K 7, 29, 30 which is not well understood but might
be related to crystal defects 26 or spin-freezing effects13. The CrSBr crystal
consists of layers with rectangular unit cells in the plane ($\hat{a}$ \-
$\hat{b}$) which are stacked along the $\hat{c}$ axis to produce an
orthorhombic structure [Figure 1(b)]. The optical properties of CrSBr reflect
its highly anisotropic electronic and magnetic structure. A prominent example
is the coupling of excitons to the magnetic order. Changes in the static
magnetic configuration induced by applying a magnetic field, for instance,
directly impact the exciton energy. The electronic band structure, and
consequently the energy of excitons in CrSBr, are sensitive to the interlayer
magnetic exchange interaction which can be used to probe its magnetic
properties7, 28, 30, 34.

Monolayer MoSe2 is a direct band gap semiconductor with two inequivalent
$\pm$K valleys and robust excitons 35, 36, 37, 38, 39, 40, 41, 42, 43. Under
out-of-plane magnetic fields, valley Zeeman effects and magnetic-field-induced
valley polarization are observed and these effects depend on the presence of
strain, doping and magnetic proximity effects44, 45, 46, 47, 48, 49, 50, 51,
52, 53, 54, 55, 56, 25.

Figure 1: (a) Optical microscope image of the studied ML MoSe2/bulk CrSBr vdW
heterostructure, covered with a thin layer of hBN. The thickness of our CrSBr
layer is about 35 nm (Figure S1) (b) Schematics of the crystal structure of
the heterostructure. (c) Schematics of the band alignment of ML MoSe2/bulk
CrSBr and charge transfer from the MoSe2 valence band (VB) to the CrSBr
conduction band (CB). (d) Typical PL spectra from ML MoSe2/CrSBr and
MoSe2/SiO2 regions at 3.6 K. The laser energy is 1.88 eV. (e) Color-coded map
of the linearly-polarized emission intensity as a function of the angle of in-
plane polarization. The laser excitation is linearly polarized along the
$\hat{a}$ axis (f) Polar plot of the PL intensity versus the in-plane linear
polarization angle for the most intense PL peak energy of CrSBr (1.329 eV) and
also for the exciton (X) and trion (T) emission peaks from MoSe2 on CrSBr.

Figure 1 (a) shows an optical microscope image of our MoSe2/CrSBr
heterostructure and the crystal orientations, $\hat{a}$ and $\hat{b}$, of the
CrSBr bulk crystal, while in Figure 1 (b) the MoSe2 and CrSBr crystal
structures are sketched. Figure 1 (c) presents the predicted type-III (broken-
gap) band alignment of the heterostructure. In Figure 1 (d), the PL spectrum
of CrSBr at 3.6 K is displayed in the left part. Several PL peaks are observed
below 1.4 eV and associated with excitons7, 34, 57, 58, defects26, and strong
exciton-photon coupling 59.

Figure 1 (d) shows the exciton and trion peaks in the normalized PL spectra of
MoSe2/CrSBr and MoSe2/SiO2. According to our theoretical predictions for the
band alignment [see Figures 2 (e-f)], the MoSe2 layer may be strongly p-doped,
while MoSe2 on SiO2 is usually n-doped52, 47. Therefore, the trion in
MoSe2/CrSBr is most likely a positively charged exciton. In addition, a low-
energy shoulder in the trion emission is observed which could be due to
inelastic scattering of trions by magnons, or due to localized trions at
charged impurities 60.

Figure 2: (a,c) Color-code map for circularly-polarized PL intensity from the
MoSe2/CrSBr heterostructure as a function of the in-plane magnetic field,
oriented along the in-plane easy (for $\vec{B}\parallel\hat{b}$) and
intermediate axes (for $\vec{B}\parallel\hat{a}$). The excitation is performed
using a linearly polarized laser. The PL detection is $\sigma^{-}$ for
positive magnetic fields. (b,d) Magnetic-field dependence of the MoSe2 PL
intensity of the exciton and trion emissions for both field orientations; the
MoSe2 PL intensity is sensitive to the magnetic phases of the CrSBr.
Calculated band structure with spin-orbit coupling for (e) CrSBr AFM, (f) ML
MoSe2, and (g) CrSBr FM systems. The CrSBr systems consist of 6 layers. The
horizontal dashed lines indicate the Fermi energy aligned with respect to the
vacuum levels. The bottom panels show the band structure in the region of the
blue rectangles, indicating clear differences of the AFM and FM energy levels
next to the Fermi energy.

Next, we investigate the light-polarization properties in detail. The
anisotropic optical emission of the CrSBr layer is evidenced by linear-
polarization-resolved PL measurements. Figure 1 (e) shows a color map of the
linearly-polarized PL intensity as a function of the in-plane linear
polarization angle at 3.6 K. The polar plots for these emissions are shown in
Figure 1 (f). All CrSBr PL peaks are strongly linearly polarized along the
$\hat{b}$ axis, which evidences the anisotropic electronic structure of CrSBr,
as expected. Remarkably, a clear dependence of the PL intensity on the in-
plane polarization angle is observed for both, the MoSe2 exciton [black
squares in Fig. 1 (f)] and trion [red circles in Fig. 1 (f)] emissions. This
result indicates that the MoSe2 has acquired a linear-polarization component
along the $\hat{a}$ axis probably due to magnetic proximity or photonic
effects due to the linear dichroism of CrSBr.

We have also measured the PL for different magnetic field ($\vec{B}$)
orientations. Figures 2 (a) and (c) show color maps of the MoSe2/CrSBr
magneto-PL intensity under $\vec{B}$ parallel to the in-plane easy
($\vec{B}\parallel\hat{b}$) and hard axis ($\vec{B}\parallel\hat{a}$),
respectively. For $\vec{B}\parallel\hat{b}$, the PL spectrum of CrSBr red-
shifts abruptly by about 15 meV above a field of 0.375 T and is constant above
0.375 T (see also Figures S6 and S7). This result is similar to previous
magneto-optical measurements for few-layer CrSBr28 and was explained by a
spin-flip transition from AFM to FM order also observed in magnetization
measurements26. Under $\vec{B}\parallel\hat{a}$, the PL spectrum shifts
smoothly, due to the canting of the spins along $\vec{B}$, saturating at
$B=1.075$ T beyond which the PL spectrum remains unchanged. The observed PL
red shifts of CrSBr with increasing magnetic field was explained by a
magnetization-dependent interlayer electronic coupling in the CrSBr material
28.

Remarkably, we also find that the PL intensities of the MoSe2 trion and
exciton are correlated to the field-induced phase transition in CrSBr bulk:
for $\vec{B}\parallel\hat{b}$ an abrupt change of the PL intensity of MoSe2
above the critical magnetic field of 0.375 T occurs [see Figure 2 (b) and
Figures S6 and S7], and for $\vec{B}\parallel\hat{a}$, a continuous decrease
of both MoSe2 PL intensities is present up to 1.075 T, which corresponds to
the saturation of the magnetization in CrSBr. Furthermore, the relative
intensity of the trion/exciton peaks (Figure S8) also shows an abrupt change
for $\vec{B}\parallel\hat{b}$, above the critical field 0.375 T, and a
continuous change up to 1.075 T for $\vec{B}\parallel\hat{a}$, which would
indicate an increase in the doping of MoSe2. This could be explained by a
change of charge transfer after the magnetic-field-induced phase transition.

These results can be rationalized by our first principles calculations of the
electronic band structure shown in Figures 2 (e-g). Not only the electronic
structures of CrSBr in the AFM/FM phases are different28, 61 but also their
band alignment (type-III) with respect to MoSe2 changes [see bottom panels in
Figures 2 (e-g)]. These energetic differences suggest that the charge transfer
between ML MoSe2 and CrSBr can be drastically altered when increasing the
magnetic field because of the transition from AFM to FM phases in CrSBr.

Let us now turn to the magneto-PL investigations of the MoSe2/CrSBr
heterostructure for an out-of-plane magnetic field ($\vec{B}\parallel\hat{c}$)
under linearly-polarized excitation and $\sigma^{-}$ circularly-polarized PL
detection as a function of $\vec{B}$. For CrSBr emission energies [Figure 3
(a)], a continuous red-shift of all PL peaks occurs while increasing $B$ (in
absolute value) up to a saturation field of about 2.25 T, beyond which the PL
peaks remains unchanged, consistent with previous reports 28. For MoSe2, the
color code map of PL intensity as a function of $B$ is shown in Figure 3 (b).
It also exhibits a correlation with the magnetic phase order of CrSBr. Figure
3 (c) presents the intensities of the exciton and trion PL peaks as a function
of the $B$. We observe an unusual change of the PL intensity for both, exciton
and trion, in the range of -2.25 to +2.25 T, which is correlated to the
magnetic-field-induced phase transition of CrSBr. In addition, we observe a
blue (red) shift of PL peak positions as shown in Figure 3 (b) and (d) with an
increase of positive (negative) $B$ values, resembling the effects of the
valley Zeeman splitting 47, 48.

Figure 3: Color-code map of the circularly resolved PL intensity as a function
of out-of-plane magnetic field for (a) CrSBr and (b) MoSe2/CrSBr. The laser
excitation is linearly polarized and the PL detection is $\sigma_{-}$ for
positive magnetic field. (c) PL intensity of exciton and trion peaks of
MoSe2/CrSBr as a function of magnetic field. Zeeman shift for the exciton
peaks in the region of (d) MoSe2/CrSBr and (e) MoSe2/SiO$2$. The solid lines
are the fittings to the data. The extracted $g$-factors are summarized in
Table 1. (f) Schematic representation of symmetric (dashed lines) and
asymmetric (solid lines) Zeeman shifts as function of magnetic field. The
transparent lines indicate the $\sigma^{+}$ polarization that is not being
measured.

The $B$ dependence for one particular polarization branch ($\sigma^{+}$ or
$\sigma^{-}$) of the PL peak of the exciton or trion in TMDs can be written
as50, 62, 63

$E_{i}(B)=E_{i}(B=0)+g_{i}^{j}\mu_{B}B,$ (1)

in which $\mu_{B}$ is the Bohr magneton, the subindex $i=\text{X (T)}$
identifies the exciton (trion), and the superindex $j=\pm$ denotes the
circular polarization $\sigma^{\pm}$. Equation (1) describes the Zeeman shift
of one polarization branch (the increase or decrease depends on the sign of
$g_{i}^{j}$, which is system dependent), whereas the Zeeman splitting requires
the knowledge of the Zeeman shifts for each polarization. The total $g$-factor
that modulates the Zeeman splitting is then given by
$g_{i}=g_{i}^{+}-g_{i}^{-}$. In pristine monolayer TMDs,
$g_{\text{X}}^{+}\sim-2$ and $g_{\text{X}}^{-}\sim 2$ (directly related to the
angular momenta of the valence and conduction band states at the K valleys
involved in the exciton transition53, 64), leading to a total $g$-factor of
$g_{\text{X}}\sim-4$. Furthermore, time reversal symmetry connects the
$g$-factors obtained at positive and negative magnetic fields via
$g_{i}^{+}(B>0)=-g_{i}^{-}(B<0)$, allowing us to recover the Zeeman shift of
the $\sigma^{+}$ branch by measuring the $\sigma^{-}$ branch at negative
magnetic fields.

Table 1: Exciton and trion $g$-factors for $B>0$. The $g$-factors for $\sigma^{+}$ were obtained via $g_{i}^{+}=-g_{i}^{-}(B<0)$ and the total $g$-factor is given by $g_{i}=g_{i}^{+}-g_{i}^{-}$. In the AFM phase, acessed by small fields, the Zeeman shifts approach the spectral resolution of the system, resulting in higher error bars for the obtained values. Nevertheless, the errors are still smaller than the extracted $g$-factors and allow us to unambiguously identify the asymmetric signatures. |  |  | MoSe2/SiO2 |  | MoSe2/CrSBr
---|---|---|---|---|---
|  |  |  |  | AFM |  | FM
| $g_{\text{X}}^{+}$ |  | $-1.98\pm 0.05$ |  | $-1.75\pm 0.39$ |  | $-0.90\pm 0.05$
Exciton | $g_{\text{X}}^{-}$ |  | $\;\;1.97\pm 0.05$ |  | $\;\;1.25\pm 0.44$ |  | $\;\;2.37\pm 0.05$
| $g_{\text{X}}$ |  | $-4.0\pm 0.1$ |  | $-3.0\pm 0.8$ |  | $-3.3\pm 0.1$
| $g_{\text{T}}^{+}$ |  | $-2.10\pm 0.05$ |  | $-1.33\pm 0.18$ |  | $-1.42\pm 0.06$
Trion | $g_{\text{T}}^{-}$ |  | $\;\;2.14\pm 0.05$ |  | $\;\;2.25\pm 0.46$ |  | $\;\;1.84\pm 0.06$
| $g_{\text{T}}$ |  | $-4.2\pm 0.1$ |  | $-3.6\pm 0.6$ |  | $-3.3\pm 0.1$

The excitonic Zeeman shift obtained for the MoSe2/CrSBr heterostructure is
displayed in Figure 3 (d). As a reference, we have also measured the magneto-
PL in the MoSe2/SiO2 region of the sample [see Figure 3 (e)]. The Zeeman
shifts of the trion peaks are presented in Figure S10 and follow closely the
excitonic features. Our results reveal an intriguing asymmetric signature in
the Zeeman shift of the MoSe2 exciton within the MoSe2/CrSBr heterostructure,
while the MoSe2/SiO2 system displays a symmetric response. These findings
point to an asymmetric coupling between the MoSe2 valleys and the CrSBr bands,
which is dependent on the magnetic ordering. Exploiting time reversal symmetry
allows us to extract distinct $g_{i}^{+}$ and $g_{i}^{-}$ values for each
magnetic phase at positive and negative magnetic fields. In Figure 3 (f), we
present a schematic representation of the symmetric and asymmetric Zeeman
shifts, summarizing the observed features of Figures 3 (d,e). The obtained
$g$-factors for excitons and trions are summarized in Table 1. Particularly,
for the excitons in MoSe2/SiO2, we extract
$\left|g_{\text{X,T}}^{+}\right|=\left|g_{\text{X,T}}^{-}\right|$ leading to a
total $g$-factor of $\sim-4.0$, consistent with theoretical53, 54, 65, 64 and
experimental values, reported in the literature for MoSe2/SiO2 or
hBN/MoSe2/hBN45, 47, 48, 66, 67, 68, 69, 70, 42, 52. For the MoSe2 excitons on
CrSBr, $\left|g_{\text{X,T}}^{+}\right|$ is distinctly different from
$\left|g_{\text{X,T}}^{-}\right|$ and the total $g$-factor is less negative
than the typical values of $-4$ in pristine MoSe2. Our study uncovers notable
variations in the $g$-factors of the MoSe2 exciton and trion when the CrSBr
undergoes transitions between the AFM and FM phases, revealing an asymmetric
coupling between the spin-valley properties of MoSe2 and the magnetic ordering
of CrSBr. These distinct $g$-factors provide valuable insights into the
intricate interplay between electronic and magnetic degrees of freedom,
underscoring the importance of considering the magnetic state of CrSBr in
understanding the behavior of excitonic systems in this heterostructure. The
changes in the magnitude of the $g$-factors are consistent with proximity
effects due to the hybridization between the layers, as previously
demonstrated in MoSe2/WSe253, 71, WSe2/CrI372, and WS2/graphene systems73. A
systematic analysis of the microscopic features behind the asymmetric
$g$-factors is beyond the scope of the current manuscript; however, we point
out that asymmetric signatures in valley Zeeman splitting have recently been
observed in MoSe2/CrBr316 heterostructures at zero magnetic field. In these
systems the magnetic moments in CrBr3 point in the out-of-plane direction and
act already as an external magnetic field. Here, the magnetic moments of CrSBr
are oriented in-plane and therefore the asymmetric coupling is manifested once
we apply an external magnetic field. The asymmetric Zeeman shifts do not
necessarily require a magnetic material but can also be present in systems
where valence bands are mixed74.

Furthermore, we have also measured the linear polarization of the PL of the
heterostructure [see Figure S4 (f)]. We find that the angle dependence and
relative intensity of the trion/exciton of the MoSe2 PL are clearly modified
as compared to 0 T. The observed anisotropy of the relative intensities of
MoSe2 trion/exciton could be explained by an anisotropic band structure of the
heterostructure due to proximity effects.

We now analyze the temperature dependence of the PL data shown in Figure 4.
For CrSBr, a blue shift of the PL band is observed with decreasing
temperature, which is accompanied by a change in the peak shape around the
magnetic phase transition ($T_{N}$ around 132 K). In addition, at 40 K, sharp
peaks appear below 1360 meV, together with a clear enhancement of the PL
intensity of the peak at around 1330 meV. A clear correlation between the
emission peaks and phase transitions in CrSBr is thus present.

Important changes are also observed for the PL of MoSe2. At higher
temperatures ($T_{N}$ > 132 K), the trion binding energy of MoSe2/CrSBr is
much lower than that of MoSe2/SiO2, probably due to different dielectric
constant values of CrSBr and SiO2. Remarkably, we find an anomalous
temperature dependence of the exciton and trion peak positions for
MoSe2/CrSBr. This is visualized in Figure 4 (d) (see also Figures S11 and
S12), where we plot the extracted trion binding energies versus temperature.
The MoSe2/CrSBr trion binding energy increases with decreasing temperature
between the magnetic phase transitions, while it stabilizes above $T_{N}$ and
below 40 K. A similar anomaly was observed in the temperature dependence of
excitons in the MoSe2/MnPSe3 heterostructure near $T_{N}$, and was associated
to a coupling of MoSe2 excitons to magnons in MnPSe33. In our heterostructure,
MoSe2 excitons may also couple to the (incoherent) magnons 57 of CrSBr at non-
zero temperatures. The impact of these magnons on the CrSBr band structure has
not yet been studied in detail, but it is expected that magnon-induced changes
will affect both the charge transfer between MoSe2 and CrSBr as well as the
dielectric screening experienced by the excitons in MoSe2. Both phenomena may
contribute to the exciton/trion temperature dependence 75, 76, 77, 78.
However, further studies will be necessary to understand in more detail this
experimental result.

Figure 4: (a) Color-code map of PL intensity as a function of temperature for
the PL peaks of the CrSBr. The highest dot-dashed line indicates the CrSBr
Néel temperature transition at 132 K, and the lower one at 40 K indicates the
temperature where sharpening of the peaks appears. (b,c) Color-code maps of
the PL intensity as a function of the temperature for the exciton and trion
peaks from (b) MoSe2/CrSBr and (c) MoSe2/SiO2. (d) Trion binding energy
extracted from the data shown in (c) and (d).

In summary, we have measured the linearly and circularly polarized PL on
MoSe2/CrSBr heterostructures under magnetic fields up to 9 T oriented along
the different crystallographic axes of CrSBr . The results show that the
valley and excitonic properties (intensity, energy position, and $g$-factors)
of monolayer MoSe2 are strongly influenced by the magnetic order of a CrSBr
substrate. For all magnetic field orientations we found that the MoSe2 PL
intensity is sensitive to the magnetic ordering of the CrSBr. We predict a
type-III band alignment for MoSe2/CrSBr which can account for the observed
correlation of MoSe2 PL intensity with the magnetic induced phase transition
of CrSBr. For out-of-plane magnetic fields, a clear asymmetric Zeeman shift is
observed for MoSe2/CrSBr. Furthermore, we observe an anomalous behaviour of
the trion binding energy as a function of temperature. The binding energy is
considerably low at high temperatures and increases below $T_{N}$. In general,
our results are explained by asymmetric magnetic proximity, charge transfer,
exciton/trion magnon coupling and dielectric anomalies of the 2D
antiferromagnetic material. Our findings offer a unique insight into the
interplay of proximity effects and charge transfer in antiferromagnetic-
nonmagnetic interfaces that modify the exciton and valley properties of 2D
TMDs.

This work was supported by Fundação de Amparo a Pesquisa do Estado de São
Paulo (FAPESP) (grants 22/08329-0 and 23/01313-4) and by the Brazilian Council
for Research (CNPq) (grant 311678/2020-3). CSB acknowledges the financial
support of CAPES fellowship. TSG and HvdZ received funding from European Union
Horizon 2020 research and innovation program under grant agreement No. 863098
(SPRING). PEFJ, KZ, CS, and JF acknowledge the financial support of the
Deutsche Forschungsgemeinschaft (DFG, German Research Foundation) SFB 1277
(Project-ID 314695032, projects B05, B07 and B11), SPP 2244 (Project No.
443416183, SCHU1171/10), and of the European Union Horizon 2020 Research and
Innovation Program under Contract No. 881603 (Graphene Flagship). YGG and HvdZ
acknowledge support from the Fapesp-SPRINT project (grant 22/00419-0). K.W.
and T.T. acknowledge support from the JSPS KAKENHI (Grant Numbers 21H05233 and
23H02052) and World Premier International Research Center Initiative (WPI),
MEXT, Japan. S.M.-V. acknowledges the European Commission for a Marie
Sklodowska–Curie individual fellowship No. 101103355 - SPIN-2D-LIGHT. J.I.A.
acknowledges support from the European Union’s Horizon 2020 research and
innovation programme for a Marie Sklodowska–Curie individual fellowship No.
101027187-PCSV. F.D. acknowledges financial support from Alexey Chernikov and
the Würzburg-Dresden Cluster of Excellence on Complexity and Topology in
Quantum Matter ct.qmat (EXC 2147, Project-ID 390858490).

The following files are available free of charge.

  * •

SI: Sample preparation, experimental methods and complementary PL results.
Details on the first principles calculations. (PDF)

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