Limits...
Observation of current-induced, long-lived persistent spin polarization in a topological insulator: A rechargeable spin battery

View Article: PubMed Central - PubMed

ABSTRACT

We report a current-induced, persistent, long-lived, and rewritable electron spin polarization in a 3D topological insulator.

No MeSH data available.


Related in: MedlinePlus

Dependences of the spin signal on out-of-plane B field component, gate voltage, and temperature.(A and B) Effect of perpendicular (out-of-plane) magnetic field on spin signals. In this experiment, the magnetic B field was tilted away from the sample (device A) surface plane (x-y) by an angle θ [depicted in the inset in (A)]. Data are measured at Id = −100 nA and T = 0.3 K. (A) Magnetic field dependence of the voltage at different angles. (B) The coercive field Bc [marked in (A) for the θ = 54° (trace)], Bc·cosθ (in-plane component of Bc), and spin signal δV as functions of θ. (C and D) Gate dependence of the spin signal measured on device D. (C) The measured voltage V as a function of the in-plane magnetic field measured at T = 1.6 K and Id = −1 μA (top) and 1 μA (bottom) at various back-gate voltages Vg. (D) The extracted spin signal δV (left axis; black symbols) and the voltage V0 (right axis; red dashed line; measured at B = 0 T before performing the spin potentiometry) as a function of Vg. The measurements were performed at T = 1.6 K. (E) Temperature T dependence of the measured spin signal from device E up to 76 K. Devices D and E have a four-terminal configuration (Fig. 2B)
© Copyright Policy - open-access
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC5392024&req=5

Figure 4: Dependences of the spin signal on out-of-plane B field component, gate voltage, and temperature.(A and B) Effect of perpendicular (out-of-plane) magnetic field on spin signals. In this experiment, the magnetic B field was tilted away from the sample (device A) surface plane (x-y) by an angle θ [depicted in the inset in (A)]. Data are measured at Id = −100 nA and T = 0.3 K. (A) Magnetic field dependence of the voltage at different angles. (B) The coercive field Bc [marked in (A) for the θ = 54° (trace)], Bc·cosθ (in-plane component of Bc), and spin signal δV as functions of θ. (C and D) Gate dependence of the spin signal measured on device D. (C) The measured voltage V as a function of the in-plane magnetic field measured at T = 1.6 K and Id = −1 μA (top) and 1 μA (bottom) at various back-gate voltages Vg. (D) The extracted spin signal δV (left axis; black symbols) and the voltage V0 (right axis; red dashed line; measured at B = 0 T before performing the spin potentiometry) as a function of Vg. The measurements were performed at T = 1.6 K. (E) Temperature T dependence of the measured spin signal from device E up to 76 K. Devices D and E have a four-terminal configuration (Fig. 2B)

Mentions: Figure 4 shows various studies of the dependences of the Id-independent spin signal (in the small Id region) on the out-of-plane component of the B field, gate voltage, and temperature. Figure 4A shows the voltage V measured on device A as a function of B field titled away from the surface at various different angles θ (depicted in the inset of Fig. 4A). We see that the coercive field (BC; labeled in Fig. 4A) increases as θ increases, whereas the in-plane component of the coercive field (BC·cosθ) and the measured spin signal δV are independent of θ, as summarized in Fig. 4B. Our results demonstrate that the spin signal δV is independent on the out-of-plane component of the magnetic field and also suggest the absence of the Hanle effect in our TI system. It is known that the Fermi level of a bulk-insulating TI sample can be tuned by gating. Figure 4C shows the spin potentiometric measurements at Id = ±1 μA on device D (a 17-nm-thick flake) at different back-gate voltages. The extracted spin signals δV and the corresponding voltage V0 (measured separately at B = 0 T) as functions of the back-gate voltage Vg are presented in Fig. 4D. When Vg is tuned from 50 to −170 V, V0 measured at Id = 1 μA exhibits an on-off ratio of ~2, and the spin signal δV is significantly enhanced as the Fermi level is tuned closer to the charge neutrality point of TSS at a negative Vg (Fig. 4, C and D). We further found that the detected Id-independent spin signal δV measured on device E (a ~20-nm-thick flake) decreases with increasing temperature T and is observable up to ~76 K (Fig. 4E and fig. S8).


Observation of current-induced, long-lived persistent spin polarization in a topological insulator: A rechargeable spin battery
Dependences of the spin signal on out-of-plane B field component, gate voltage, and temperature.(A and B) Effect of perpendicular (out-of-plane) magnetic field on spin signals. In this experiment, the magnetic B field was tilted away from the sample (device A) surface plane (x-y) by an angle θ [depicted in the inset in (A)]. Data are measured at Id = −100 nA and T = 0.3 K. (A) Magnetic field dependence of the voltage at different angles. (B) The coercive field Bc [marked in (A) for the θ = 54° (trace)], Bc·cosθ (in-plane component of Bc), and spin signal δV as functions of θ. (C and D) Gate dependence of the spin signal measured on device D. (C) The measured voltage V as a function of the in-plane magnetic field measured at T = 1.6 K and Id = −1 μA (top) and 1 μA (bottom) at various back-gate voltages Vg. (D) The extracted spin signal δV (left axis; black symbols) and the voltage V0 (right axis; red dashed line; measured at B = 0 T before performing the spin potentiometry) as a function of Vg. The measurements were performed at T = 1.6 K. (E) Temperature T dependence of the measured spin signal from device E up to 76 K. Devices D and E have a four-terminal configuration (Fig. 2B)
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC5392024&req=5

Figure 4: Dependences of the spin signal on out-of-plane B field component, gate voltage, and temperature.(A and B) Effect of perpendicular (out-of-plane) magnetic field on spin signals. In this experiment, the magnetic B field was tilted away from the sample (device A) surface plane (x-y) by an angle θ [depicted in the inset in (A)]. Data are measured at Id = −100 nA and T = 0.3 K. (A) Magnetic field dependence of the voltage at different angles. (B) The coercive field Bc [marked in (A) for the θ = 54° (trace)], Bc·cosθ (in-plane component of Bc), and spin signal δV as functions of θ. (C and D) Gate dependence of the spin signal measured on device D. (C) The measured voltage V as a function of the in-plane magnetic field measured at T = 1.6 K and Id = −1 μA (top) and 1 μA (bottom) at various back-gate voltages Vg. (D) The extracted spin signal δV (left axis; black symbols) and the voltage V0 (right axis; red dashed line; measured at B = 0 T before performing the spin potentiometry) as a function of Vg. The measurements were performed at T = 1.6 K. (E) Temperature T dependence of the measured spin signal from device E up to 76 K. Devices D and E have a four-terminal configuration (Fig. 2B)
Mentions: Figure 4 shows various studies of the dependences of the Id-independent spin signal (in the small Id region) on the out-of-plane component of the B field, gate voltage, and temperature. Figure 4A shows the voltage V measured on device A as a function of B field titled away from the surface at various different angles θ (depicted in the inset of Fig. 4A). We see that the coercive field (BC; labeled in Fig. 4A) increases as θ increases, whereas the in-plane component of the coercive field (BC·cosθ) and the measured spin signal δV are independent of θ, as summarized in Fig. 4B. Our results demonstrate that the spin signal δV is independent on the out-of-plane component of the magnetic field and also suggest the absence of the Hanle effect in our TI system. It is known that the Fermi level of a bulk-insulating TI sample can be tuned by gating. Figure 4C shows the spin potentiometric measurements at Id = ±1 μA on device D (a 17-nm-thick flake) at different back-gate voltages. The extracted spin signals δV and the corresponding voltage V0 (measured separately at B = 0 T) as functions of the back-gate voltage Vg are presented in Fig. 4D. When Vg is tuned from 50 to −170 V, V0 measured at Id = 1 μA exhibits an on-off ratio of ~2, and the spin signal δV is significantly enhanced as the Fermi level is tuned closer to the charge neutrality point of TSS at a negative Vg (Fig. 4, C and D). We further found that the detected Id-independent spin signal δV measured on device E (a ~20-nm-thick flake) decreases with increasing temperature T and is observable up to ~76 K (Fig. 4E and fig. S8).

View Article: PubMed Central - PubMed

ABSTRACT

We report a current-induced, persistent, long-lived, and rewritable electron spin polarization in a 3D topological insulator.

No MeSH data available.


Related in: MedlinePlus