Fig. 1. (Color online) Characterization of the Fe-SnS₂ flakes. (a) The atomic structure of Fe-SnS₂. One Sn atom is replaced by one Fe atom and surrounded by six Sn atoms. (b) Raman spectra of Fe-SnS₂ and SnS₂ flakes. (c) EDS of the Fe-SnS₂ flake. Inset is a partially enlarged view of the characteristic peaks of Fe. (d) Low-resolution TEM image of the Fe-SnS₂ flake. (e) High resolution TEM image of Fe-SnS₂ flake. (f) SAED patterns of Fe-SnS₂ flake.

Fig. 2. (Color online) (a) Schematic diagram of Fe-SnS₂ homojunction device. (b) AFM image of a typical device. On the right-hand is the corresponding optical microscope image, and the relative direction of the applied magnetic field is marked. The scale is 5μm. (c)I–V_ds curves at zero magnetic field, 14 T vertical magnetic field and 14 T parallel magnetic field. The inset is an enlarged view of the conduction part.

Fig. 3. (Color online) MR of the Fe-SnS₂ homojunction device under parallel magnetic field. (a)I–V_ds curves under different magnetic fields. (b) Dependence of MR on magnetic field extracted fromI_ds–B curves atV_ds = –7 V. (c) Extracted MR as a function of bias based on theI–V_ds curves at zero magnetic field and 14 T. There is a peak value of MR atV_ds ~ –6.5 V.

Fig. 4. (Color online) MR of the Fe-SnS₂ homojunction device under vertical magnetic field. (a)I–V_ds curves under different magnetic fields. (b) Dependence of MR on magnetic field extracted fromI_ds–B curves atV_ds = –7 V. The magnetic field direction is vertical to the device plane. (c) Extracted MR as a function of bias based on theI–V_ds curves at zero magnetic field and 14 T. There is a peak value of MR atV_ds ~ –6.2 V.

Fig. 5. (Color online)V_g dependence of the Fe-SnS₂ homojunction device.I–V_ds curves under different gate voltages in (a) parallel and (b) vertical magnetic fields. The black line is the curve at 14 T and the red line is the curve at zero magnetic field. At large negativeV_g (–8 V and –5 V), MR tends to infinity under parallel magnetic field.