Data from: Fieldfree deterministic switching of allvan der Waals spinorbit torque system above room temperature
Data files
Feb 21, 2024 version files 12.43 MB

DFTCodes_and_Data.zip

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README.md

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Abstract
Twodimensional van der Waals (vdW) magnetic materials hold promise for the development of highdensity, energyefficient spintronic devices for memory and computation. Recent breakthroughs in material discoveries and spinorbit torque (SOT) control of vdW ferromagnets have opened a path for integration of vdW magnets in commercial spintronic devices. However, a solution for fieldfree electric control of perpendicular magnetic anisotropy (PMA) vdW magnets at room temperatures, essential for building compact and thermally stable spintronic devices, is still missing. Here, we report a solution for the fieldfree, deterministic and nonvolatile switching of a PMA vdW ferromagnet, Fe_{3}GaTe_{2} above room temperature (up to 320 K). We use the unconventional outofplane antidamping torque from an adjacent WTe_{2} layer to enable such switching with a low current density of 2.23 × 10^{6} A cm^{2}. This study exemplifies the efficacy of lowsymmetry vdW materials for spinorbit torque control of vdW ferromagnets and provides an allvdW solution for the next generation of scalable and energyefficient spintronic devices.
README: Fieldfree deterministic switching of allvan der Waals spinorbit torque system above room temperature
https://doi.org/10.5061/dryad.s7h44j1dh
Raw data used in generating all the plots in the manuscript (main text and supplementary) is provided here in spreadsheet format. One file is created for every composite figure, and the data from constituent subfigures is added to separate pages of the file.
For the DFT calculations using Quantum Espresso, input files, output files and output data are attached separately as a zipped file. A separate README file is provided in the zipped file which describes organisation of the DFT codes and results.
Below we provide detailed description of the data (abbreviations, data arrangement) for all the figures.
Fig. 1
(D) Raman spectroscopy data for the device D1. First column is the Raman shift, while subsequent columns give the Raman intensity for different angles, Phi (0, 3, 6, ..., 357, 360 degree)
Fig. 2
(A) Anomalous Hall effect data for device D1, at different temperatures (260, 280, 300, 320, 330, 340K). For each temperature, 4 columns of data are provided  backward field (H), backward Hall resistance (Rxy), forward field (H) and forward Hall resistance (Rxy), respectively.
(B) Anomalous Hall effect data for device D1, at different temperatures (10, 50, 100, 150, 200K). For each temperature, 4 columns of data are provided  backward field (H), backward Hall resistance (Rxy), forward field (H) and forward Hall resistance (Rxy), respectively.
(C) Variation of anomalous Hall resistance (RxyAHE) and coercivity in the device D1 for varying temperatures (T). These values are derived from the curves in Fig. 2A and 2B.
(D) Anomalous Hall resistance for device D1, for field swept in the plane of the device. Four columns of data are provided  backward field (H), backward Hall resistance (Rxy), forward field (H) and forward Hall resistance (Rxy), respectively.
Fig. 3
(B) Anomalous Hall resistance of device D2 (resistance vs current) for the 4 cases  current pulses swept from (0 to 4.5 mA to 0) or (0 to 4.5 mA to 0 mA), for the device initialized at m =1 and m = 1.
(C) Current induced switching in device D2 (resistance vs current) for the two cases  negative and positive external field.
(D) Time series of Hall resistance measurement  time and resistance.
Fig. 4
(A) Switching data, for different temperatures (300, 305, ..., 330K). For each temperature, there are five columns  current (I) and four resistance (R). Plotted data shows the mean and standard deviation of the four resistances at that temperature.
(C) Switched resistance (RxyAHE) for different temperatures (T). The data points are derived from the curves in figure 4A.
(D) Time series of Hall resistance measurement  time and resistance. Two pieces, each 50 second long, are provided.
SuppFig. 1
(C) Atomic force microscopy (AFM) line profile  xcoordinate and height.
SuppFig. 2
(B) Raman spectroscopy data for the device D2. First column is the Raman shift, while subsequent columns give the Raman intensity for different angles, Phi (0, 6, 12, ..., 354, 360 degree).
(E) Atomic force microscopy (AFM) line profile  xcoordinate and height.
(G) Atomic force microscopy (AFM) line profile  xcoordinate and height.
SuppFig. 3
(A) Anomalous Hall effect data for device D2, at different temperatures (260, 280, 300, 320, 340K). For each temperature, 4 columns of data are provided  backward field (H), backward Hall resistance (Rxy), forward field (H) and forward Hall resistance (Rxy), respectively.\
(B) Anomalous Hall effect data for device D2, at different temperatures (10, 50, 100, 150, 200, 250K). For each temperature, 4 columns of data are provided  backward field (H), backward Hall resistance (Rxy), forward field (H) and forward Hall resistance (Rxy), respectively.\
(C) Variation of anomalous Hall resistance (RxyAHE) and coercivity in the device D2 for varying temperatures (T). These values are derived from the curves in SuppFig. 3A and 3B.\
(D) Anomalous Hall resistance for device D2, for field swept in the plane of the device. Four columns of data are provided  backward field (H), backward Hall resistance (Rxy), forward field (H) and forward Hall resistance (Rxy), respectively.
SuppFig. 4
(A) Current induced switching in device D2 at 300 K (resistance vs current) for current swept up to a maximum of +/ 7 mA.
(B) Current induced switching in device D2 at 300 K (resistance vs current) for current swept up to a maximum of +/ 8 mA. Data for this case is the average of four consecutive sweeps. Data corresponding to individual sweeps in presented in SuppFig. 5A.
(C) Current induced switching in device D2 at 300 K (resistance vs current) for current swept up to a maximum of +/ 9 mA.
(D) Current induced switching in device D2 at 300 K (resistance vs current) for current swept up to a maximum of +/ 10 mA.
SuppFig. 5
(A) Data for four consecutive cyclic current sweeps (loops) at 300 K. Single current coloum is provided which is common for all four sweeps. Four coloumns of resistance (Rxy) recorded for the four sweeps (loops L1L4) are provided next.
(B) Data for four consecutive cyclic current sweeps at 305 K. Single current coloum is provided which is common for all four sweeps. Four coloumns of resistance (Rxy) recorded for the four sweeps are provided next.
(C) Data for four consecutive cyclic current sweeps at 310 K. Single current coloum is provided which is common for all four sweeps. Four coloumns of resistance (Rxy) recorded for the four sweeps are provided next.
(D) Data for four consecutive cyclic current sweeps at 315 K. Single current coloum is provided which is common for all four sweeps. Four coloumns of resistance (Rxy) recorded for the four sweeps are provided next.
(E) Data for four consecutive cyclic current sweeps at 320 K. Single current coloum is provided which is common for all four sweeps. Four coloumns of resistance (Rxy) recorded for the four sweeps are provided next.
(F) Data for four consecutive cyclic current sweeps at 325 K. Single current coloum is provided which is common for all four sweeps. Four coloumns of resistance (Rxy) recorded for the four sweeps are provided next.
SuppFig. 6
Time series of Hall resistance measurement  time and resistance (Rxy). Two pieces, each 50 second long, are provided for temperatures 300 K and 310 K.
Methods
Device Morphology
Thicknesses of the constituent flakes were characterized after encapsulation using a Cypher VRS AFM. Polarized Raman spectra of WTe_{2} flakes was acquired using a 532 nm laser with a WITec Alpha300 Apyron Confocal Raman microscope, by rotating the polarizer and analyzer while the sample was static.
Transport Measurements
All transport measurements were performed in a 9 T PPMS DynaCool system. Measurements were performed by sourcing current using a Keithley 6221 current source and measuring the transverse voltage across the devices, using a Keithley 2182A nanovoltmeter. Anomalous Hall effect measurements with field sweeps were performed using a drive current of 50 – 200 A. For the currentinduced switching measurements, a 1 ms pulse of writecurrent was followed by 999 ms of read pulses ( 200 A). Field could be applied in and out of the sample plane using the PPMS’ horizontal rotator module.
First Principles Calculations
Electronic properties calculation and structural optimizations were performed using density functional theory (DFT) with the Quantum ESPRESSO package. We use the optimized normconserving Vanderbilt (ONCV) pseudopotentials with PerdewBurkeErnzerhof (PBE) functionals to account for the exchangecorrelation interaction. To accurately describe the structural properties of layered FGaT structure, we use the nonlocal vdWDF2 functional for the van der Waals interaction. A large plane wave cutoff energy of 60 Ry (~ 816 eV) is used for all calculations. The FGaT monolayer and bilayer are modeled by the slab supercells, with the separations between the neighboring slabs being about 20 Å. A 16×16×1 kpoint mesh is used for monolayer and bilayer FGaT, while 14×14×2 mesh is used for the bulk FGaT. These parameters are selected based on the convergence test of the total energy. The atomic positions and lattice constants are optimized by the BFGS quasinewton algorithm, in which the convergence values for the forces and stress components are 0.0001 Ry/a.u.^{3} and 0.005 GPa, respectively. To determine the magnetic anisotropy energy (MAE) of FGaT, we first perform the total energy calculations for an inplane magnetization (along the xaxis) and then outofplane magnetization (along the zaxis), including spinorbit coupling (SOC). Then, the MAE is given by the difference in total energy for the two systems.