Research ArticleCONDENSED MATTER PHYSICS

Current-driven magnetization switching in a van der Waals ferromagnet Fe3GeTe2

See allHide authors and affiliations

Science Advances  23 Aug 2019:
Vol. 5, no. 8, eaaw8904
DOI: 10.1126/sciadv.aaw8904
  • Fig. 1 Schematic view and characterizations of FGT/Pt bilayer.

    (A) Schematic view of the bilayer structure. Pt layer (top) is sputtered on top of the exfoliated FGT (bottom). The green arrow represents the in-plane current flowing in the Pt layer, which generates a spin current flowing in the z direction. The accumulated spins at the bottom (top) Pt surface are indicated by the red (blue) arrows. The spin current exerts torques on the magnetization of FGT and can switch it in the presence of an in-plane magnetic field. (B) Cross-sectional STEM image of the FGT/Pt device fabricated on a Si/SiO2 substrate. The total thickness of FGT is 12.6 nm. (C) High-resolution STEM image of an FGT (87 nm)/Pt (6 nm) bilayer on a Si/SiO2 substrate. (D) Top view of the FGT exfoliated from the bulk material measured by atomic force microscopy. (E) The atomic steps profile taken along the yellow dashed lines in (D). An atomic layer step of 0.8 nm is observed. (F) The optical image of the measured Hall bar device. (G) Temperature-dependent longitudinal resistance of the FGT/Pt bilayer device and FGT only.

  • Fig. 2 Magnetic properties of FGT/Pt bilayer.

    (A) Hall resistance as a function of magnetic field at different temperatures. (B) Arrott plots of the Hall resistance of the FGT/Pt device. The determined Tc is 158 K. (C) RAHE as a function of in-plane (IP) and out-of-plane (OOP) magnetic field at 90 K.

  • Fig. 3 Characterization of the current-induced effective fields.

    (A and B) First and second harmonic voltages for the longitudinal effective field. HL is the applied longitudinal magnetic field along the current direction (x axis). (D and E) First and second harmonic voltages for the transverse effective field. HT is the applied transverse magnetic field transverse to the current direction (y axis). (C and F) Plots of the longitudinal and transverse field as a function of the peak current. The solid lines represent the linear fitting result with zero intercept. The red circles (blue squares) are data points for the Mz > 0 (Mz < 0). In the bilayer device, applying a current of 1 mA corresponds to a current density of 1.85 × 1010 A/m2 in the Pt layer.

  • Fig. 4 SOT-driven perpendicular magnetization switching in the FGT/Pt bilayer device.

    Current-driven perpendicular magnetization switching for in-plane magnetic fields of 50 mT (A) and −50 mT (B) at 100 K. The switching polarity is anticlockwise and clockwise, respectively. The dashed lines correspond to the RAHE at saturated magnetization states. (C) Current-driven perpendicular magnetization switching with a 300-mT in-plane magnetic field at 10 K (red). The arrows indicate the current sweeping direction. The initial state is saturated in the positive direction. The current increases gradually in the positive direction, and the RAHE jumps down to an intermediate state. The two states in the switching loop do not correspond to the saturated states. The device temperature during the application of switching current (blue) is obtained by comparing the measured longitudinal resistance and the measured RxxT curve (fig. S14). The dashed line corresponds to the Tc obtained from the Arrott plots. (D) Switching-phase diagram with respect to the in-plane magnetic fields and critical switching currents at different temperatures. The critical switching current decreases with increasing temperature. In the bilayer device, applying a current of 1 mA corresponds to a current density of 1.85 × 1010 A/m2 in the Pt layer.

Supplementary Materials

  • Supplementary material for this article is available at http://advances.sciencemag.org/cgi/content/full/5/8/eaaw8904/DC1

    Section S1. Crystal growth and characterization

    Section S2. Exfoliation of FGT thin flakes and fabrication of FGT/Pt bilayer devices

    Section S3. Correction of current-induced effective fields

    Section S4. Current-driven switching at different temperatures

    Section S5. Current-driven magnetization switching

    Section S6. Current-driven magnetization switching and measurement of effective fields corresponding the current-induced torques

    Section S7. Temperature dependence of PMA

    Fig. S1. Single crystals of FGT at the colder side in a sealed quartz tube (diameter of the tube is 1.5 cm).

    Fig. S2. Characterization of FGT single crystal grown by CVT method.

    Fig. S3. Zero-field–cooling and field-cooling curves of the FGT crystals (grown by CVT) measured from 10 to 300 K with the external magnetic field (H = 0.1 T) parallel to the c axis.

    Fig. S4. Hysteresis loops measured of the FGT crystals (grown by CVT) at various temperatures with the external magnetic field parallel to the c axis.

    Fig. S5. Zero-field–cooling and field-cooling curves of the FGT crystals (grown by CVT method) measured from 10 to 300 K with the external magnetic field (H = 0.1 T) parallel to the ab plane.

    Fig. S6. Hysteresis loops of the FGT crystals (grown by CVT method) measured at various temperatures with the external magnetic field parallel to the ab plane.

    Fig. S7. Zero-field–cooling and field-cooling curves of the FGT crystals (grown by CVT) measured from 10 to 300 K with the external magnetic field (H = 0.1 T) parallel to the c axis and the ab plane.

    Fig. S8. Characterization of FGT single crystal grown by flux method.

    Fig. S9. Zero-field–cooling and field-cooling curves of the FGT crystals (grown by flux method) measured from 10 to 300 K with the external magnetic field (H = 0.1 T) parallel to the c axis.

    Fig. S10. Hysteresis loops measured of the FGT crystals (grown by flux method) at various temperatures with the external magnetic field parallel to the c axis.

    Fig. S11. Schematic view of FGT exfoliation, transfer, and device fabrication process.

    Fig. S12. Atomic force microscopy image of the obtained FGT flakes on SiO2 substrate through two strategies.

    Fig. S13. Optical image of the device fabrication process.

    Fig. S14. Estimation of the temperature dependence of the resistance of FGT layers.

    Fig. S15. Schematic diagram of measurement setup and coordinate system.

    Fig. S16. Current-driven switching at 10 K.

    Fig. S17. Current-driven switching at 20 K.

    Fig. S18. Current-driven switching at 30 K.

    Fig. S19. Current-driven switching at 40 K.

    Fig. S20. Current-driven switching at 50 K.

    Fig. S21. Current-driven switching at 60 K.

    Fig. S22. Current-driven switching at 70 K.

    Fig. S23. Current-driven switching at 80 K.

    Fig. S24. Current-driven switching at 90 K.

    Fig. S25. Current-driven switching at 100 K.

    Fig. S26. Current-driven switching at 110 K.

    Fig. S27. Current-driven switching at 120 K.

    Fig. S28. Current-driven switching at 130 K.

    Fig. S29. Rxy as a function of current under different in-plane magnetic field at 140 K.

    Fig. S30. Current-driven magnetization switching for different initial states.

    Fig. S31. Current-driven switching in an FGT/Ta bilayer.

    Fig. S32. Characterization of the current-induced effective fields in an FGT/Ta device.

    Fig. S33. Hall resistance as a function of in-plane magnetic field.

    Fig. S34. Temperature dependence of effective anisotropy field (μ0Hk), coercivity (μ0Hc), and saturation anomalous Hall resistance.

    References (3335)

  • Supplementary Materials

    This PDF file includes:

    • Section S1. Crystal growth and characterization
    • Section S2. Exfoliation of FGT thin flakes and fabrication of FGT/Pt bilayer devices
    • Section S3. Correction of current-induced effective fields
    • Section S4. Current-driven switching at different temperatures
    • Section S5. Current-driven magnetization switching
    • Section S6. Current-driven magnetization switching and measurement of effective fields corresponding the current-induced torques
    • Section S7. Temperature dependence of PMA
    • Fig. S1. Single crystals of FGT at the colder side in a sealed quartz tube (diameter of the tube is 1.5 cm).
    • Fig. S2. Characterization of FGT single crystal grown by CVT method.
    • Fig. S3. Zero-field–cooling and field-cooling curves of the FGT crystals (grown by CVT) measured from 10 to 300 K with the external magnetic field (H = 0.1 T) parallel to the c axis.
    • Fig. S4. Hysteresis loops measured of the FGT crystals (grown by CVT) at various temperatures with the external magnetic field parallel to the c axis.
    • Fig. S5. Zero-field–cooling and field-cooling curves of the FGT crystals (grown by CVT method) measured from 10 to 300 K with the external magnetic field (H = 0.1 T) parallel to the ab plane.
    • Fig. S6. Hysteresis loops of the FGT crystals (grown by CVT method) measured at various temperatures with the external magnetic field parallel to the ab plane.
    • Fig. S7. Zero-field–cooling and field-cooling curves of the FGT crystals (grown by CVT) measured from 10 to 300 K with the external magnetic field (H = 0.1 T) parallel to the c axis and the ab plane.
    • Fig. S8. Characterization of FGT single crystal grown by flux method.
    • Fig. S9. Zero-field–cooling and field-cooling curves of the FGT crystals (grown by flux method) measured from 10 to 300 K with the external magnetic field (H = 0.1 T) parallel to the c axis.
    • Fig. S10. Hysteresis loops measured of the FGT crystals (grown by flux method) at various temperatures with the external magnetic field parallel to the c axis.
    • Fig. S11. Schematic view of FGT exfoliation, transfer, and device fabrication process.
    • Fig. S12. Atomic force microscopy image of the obtained FGT flakes on SiO2 substrate through two strategies.
    • Fig. S13. Optical image of the device fabrication process.
    • Fig. S14. Estimation of the temperature dependence of the resistance of FGT layers.
    • Fig. S15. Schematic diagram of measurement setup and coordinate system.
    • Fig. S16. Current-driven switching at 10 K.
    • Fig. S17. Current-driven switching at 20 K.
    • Fig. S18. Current-driven switching at 30 K.
    • Fig. S19. Current-driven switching at 40 K.
    • Fig. S20. Current-driven switching at 50 K.
    • Fig. S21. Current-driven switching at 60 K.
    • Fig. S22. Current-driven switching at 70 K.
    • Fig. S23. Current-driven switching at 80 K.
    • Fig. S24. Current-driven switching at 90 K.
    • Fig. S25. Current-driven switching at 100 K.
    • Fig. S26. Current-driven switching at 110 K.
    • Fig. S27. Current-driven switching at 120 K.
    • Fig. S28. Current-driven switching at 130 K.
    • Fig. S29. Rxy as a function of current under different in-plane magnetic field at 140 K.
    • Fig. S30. Current-driven magnetization switching for different initial states.
    • Fig. S31. Current-driven switching in an FGT/Ta bilayer.
    • Fig. S32. Characterization of the current-induced effective fields in an FGT/Ta device.
    • Fig. S33. Hall resistance as a function of in-plane magnetic field.
    • Fig. S34. Temperature dependence of effective anisotropy field (μ0Hk), coercivity (μ0Hc), and saturation anomalous Hall resistance.
    • References (3335)

    Download PDF

    Files in this Data Supplement:

Navigate This Article