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Sun et al. Soft Sci. 2025, 5, 35 https://dx.doi.org/10.20517/ss.2025.21 Page 5 of 16

Subsequently, the microstructure and internal composition of the FCNZ-500, FCNZ-600, and FCNZ-700
were further analyzed. Figure 2A-C respectively represents the TEM images of FCNZ-500, FCNZ-600, and
FCNZ-700. As the annealing temperature ascends from 500 to 600 °C, the interfacial bonding degree in the
ZnIn S -FeCoNi region in FCNZ-600 was enhanced. However, when the temperature further rose to 700 °C,
2 4
the crystal structure of ZnIn S in FCNZ-700 might be optimized to some extent, but the nanosheets tend to
2 4
agglomerate and the structural uniformity decreases. This phenomenon is also in accordance with the
corresponding permittivity results. High resolution transmission electron microscopy (HRTEM) and the
corresponding fast Fourier transform (FFT) patterns [Figure 2D-G] further validate that the FCNZ-600
composite material is composed of FeCoNi and ZnIn S . By measuring the lattice spacing, 0.223 nm
2 4
[36]
corresponded to the (110) FeCoNi [Figure 2G and G(i)] , while 0.337 and 0.196 nm corresponded to the
(101) and (110) ZnIn S [Figure 2E, E(i), and E(ii)] . Simultaneously, two lattice spacings, 0.342 and
[37]
2 4
0.218 nm, were identified at the core-shell interface, corresponding to the (101) plane of ZnIn S and the
2 4
(110) plane of FeCoNi [Figure 2F, F(i), and F(ii)], respectively. These results further confirm that the
structure of FCNZ-600 constitutes a hybrid system featuring a tight interface contact. The high-angle
annular dark-field (HAADF) image [Figure 2H] and energy-dispersive X-ray spectroscopy (EDS) spectra
[Supplementary Figure 1] show that Fe, Co, and Ni elements focus in spherical center, while Zn, In, and S
elements are displayed in the shell region. During high-temperature annealing, the thermal motion of atoms
intensifies, providing sufficient energy to drive diffusion across phase boundaries. As a result, Fe, Co, and
Ni elements diffuse from the FeCoNi core to the ZnIn S shell. This diffusion leads to the formation of a
2 4
gradient interface, thereby optimizing electronic transport and polarization behavior at the interface.

Figure 3A displays the diffraction patterns of ZnIn S annealed at 500, 600, and 700 °C. With increasing
2 4
annealing temperature, the crystallinity of the material becomes progressively more defined and
pronounced. The ZnIn S sample annealed at 700 °C corresponds to two standard reference patterns,
2 4
PDF#72-1445 and PDF#65-2023. As shown in Figure 3B, FCNZ-500, FCNZ-600, and FCNZ-700 exhibit
three prominent diffraction peaks at (110), (200), and (211), which are attributed to the face-centered cubic
(FCC) structure . However, due to the weak intensity of the ZnIn S diffraction peak [Supplementary
[26]
2 4
Figure 2], the corresponding diffraction peak was not observed in the FCNZ diffraction pattern. Figure 3C
shows the hysteresis loops of FCNZ composites annealed at different temperatures. The saturation
magnetization (M ) values of FCNZ-500, FCNZ-600, and FCNZ-700 are 124.8, 138.2, and 164.2 emu/g. The
s
higher M value is beneficial in enhancing the magnetization intensity and improving the permeability.
s
Meanwhile, the coercive force (H ) of FCNZ-500, FCNZ-600, and FCNZ-700 is 2.82, 85.7, and 27.7 Oe,
c
respectively. The difference in H may result from the anisotropy of FeCoNi and the defect distribution.
c
Interface-induced magnetic anisotropy is one of the key mechanisms to promote magnetic-dielectric
coupling. The presence of ZnIn S shell layer and its interfacial interactions with FeCoNi core significantly
2 4
change the magnetic domain structure. The FCNZ-600 samples have a high coercive force (H = 85.7 Oe).
c
The enhanced magnetic anisotropy of the FCNZ-600 helps to stimulate and strengthen the magnetic loss
mechanism, which is a key process for achieving efficient coupling and dissipation of magnetic energy .
[38]
To further reveal the composition, XPS analysis was applied on FCNZ-500, FCNZ-600, and FCNZ-700
[Figure 3D-J]. The survey X-ray photoelectron spectra of FCNZ-500, FCNZ-600, and FCNZ-70 indicate
that the samples are composed of Fe, Ni, Co, Zn, In, and S elements [Figure 3D]. In the Fe 2p spectrum
[Figure 3E], the characteristic peaks of Fe 2p and Fe 2p and the corresponding satellite peaks can be
1/2
3/2
observed in all samples, indicating different valence states of Fe. The characteristic peak corresponding to
0[39]
703.8 eV is attributed to Fe . Additionally, the peaks observed at 709.9 and 722.9 eV indicate 2p and 2p
3/2
1/2
2+
2+
of Fe , respectively, while satellite signatures at 713.4 and 726.7 eV are associated with Fe satellite peaks.
3+
Similarly, signals at 711.6 and 723.1 eV correspond to 2p and 2p of Fe , and additional satellite peaks at
3/2
1/2