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Large spin Hall magnetoresistance and its correlation to the spin-orbit torque in W/CoFeB/MgO structures.

Cho S, Baek SH, Lee KD, Jo Y, Park BG - Sci Rep (2015)

Bottom Line: This implies the existence of an inverse effect, in which the conductivity in such structures should depend on the magnetization orientation.We observe that the MR is independent of the angle between the magnetization and current direction but is determined by the relative magnetization orientation with respect to the spin direction accumulated by the spin Hall effect, for which the symmetry is identical to that of so-called the spin Hall magnetoresistance.The MR of ~1% in W/CoFeB/MgO samples is considerably larger than those in other structures of Ta/CoFeB/MgO or Pt/Co/AlOx, which indicates a larger spin Hall angle of W.

View Article: PubMed Central - PubMed

Affiliation: Department of Materials Science and Engineering, KAIST, Daejeon 305-701, Korea.

ABSTRACT
The phenomena based on spin-orbit interaction in heavy metal/ferromagnet/oxide structures have been investigated extensively due to their applicability to the manipulation of the magnetization direction via the in-plane current. This implies the existence of an inverse effect, in which the conductivity in such structures should depend on the magnetization orientation. In this work, we report a systematic study of the magnetoresistance (MR) of W/CoFeB/MgO structures and its correlation with the current-induced torque to the magnetization. We observe that the MR is independent of the angle between the magnetization and current direction but is determined by the relative magnetization orientation with respect to the spin direction accumulated by the spin Hall effect, for which the symmetry is identical to that of so-called the spin Hall magnetoresistance. The MR of ~1% in W/CoFeB/MgO samples is considerably larger than those in other structures of Ta/CoFeB/MgO or Pt/Co/AlOx, which indicates a larger spin Hall angle of W. Moreover, the similar W thickness dependence of the MR and the current-induced magnetization switching efficiency demonstrates that MR in a non-magnet/ferromagnet structure can be utilized to understand other closely correlated spin-orbit coupling effects such as the inverse spin Hall effect or the spin-orbit spin transfer torques.

No MeSH data available.


Related in: MedlinePlus

Longitudinal magnetoresistance (Rxx) for different NM underlayer.(a) Ta(5 nm)/CoFeB(1 nm)/MgO(1.6 nm) and (b) Pt(3 nm)/Co(1 nm)/AlOx(1.5 nm) samples. The black solid (red open) circles represent the data for Hx (Hy).
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f3: Longitudinal magnetoresistance (Rxx) for different NM underlayer.(a) Ta(5 nm)/CoFeB(1 nm)/MgO(1.6 nm) and (b) Pt(3 nm)/Co(1 nm)/AlOx(1.5 nm) samples. The black solid (red open) circles represent the data for Hx (Hy).

Mentions: We compare the Rxx values of the W/CoFeB/MgO samples with those of samples with different underlayers. Figure 3 shows the Rxx values of Ta/CoFeB/MgO sample (a) and Pt/Co/AlOx sample (b) as a function of two different magnetic fields of Hx (black solid symbols, and Hy (red open symbols, ). Both samples show behavior similar behavior to that of the W/CoFeB/MgO samples, i.e., a stronger dependence of Rxx on Hy rather than Hx, demonstrating that SMR is the dominant magneto-transport mechanism in these NM/FM/oxide structures. However, the magnitude of the SMR of the sample with Ta or Pt is considerably smaller than that of the W/CoFeB/MgO structure, despite the fact that it is still much larger than those of the Pt/YIG samples810111213. Because the SMR mechanism is known to be a combination of the SHE and ISHE, the larger SMR can be explained by a larger spin Hall angle of W as compared to that of Ta or Pt, which is consistent with the values reported in the literature421222930. Given that the SMR is proportional to the square of spin Hall angle9, the relative magnitude of the SMR indicates that the spin Hall angle of W is approximately three (two) times larger than that of the sample with Ta (Pt).


Large spin Hall magnetoresistance and its correlation to the spin-orbit torque in W/CoFeB/MgO structures.

Cho S, Baek SH, Lee KD, Jo Y, Park BG - Sci Rep (2015)

Longitudinal magnetoresistance (Rxx) for different NM underlayer.(a) Ta(5 nm)/CoFeB(1 nm)/MgO(1.6 nm) and (b) Pt(3 nm)/Co(1 nm)/AlOx(1.5 nm) samples. The black solid (red open) circles represent the data for Hx (Hy).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4589767&req=5

f3: Longitudinal magnetoresistance (Rxx) for different NM underlayer.(a) Ta(5 nm)/CoFeB(1 nm)/MgO(1.6 nm) and (b) Pt(3 nm)/Co(1 nm)/AlOx(1.5 nm) samples. The black solid (red open) circles represent the data for Hx (Hy).
Mentions: We compare the Rxx values of the W/CoFeB/MgO samples with those of samples with different underlayers. Figure 3 shows the Rxx values of Ta/CoFeB/MgO sample (a) and Pt/Co/AlOx sample (b) as a function of two different magnetic fields of Hx (black solid symbols, and Hy (red open symbols, ). Both samples show behavior similar behavior to that of the W/CoFeB/MgO samples, i.e., a stronger dependence of Rxx on Hy rather than Hx, demonstrating that SMR is the dominant magneto-transport mechanism in these NM/FM/oxide structures. However, the magnitude of the SMR of the sample with Ta or Pt is considerably smaller than that of the W/CoFeB/MgO structure, despite the fact that it is still much larger than those of the Pt/YIG samples810111213. Because the SMR mechanism is known to be a combination of the SHE and ISHE, the larger SMR can be explained by a larger spin Hall angle of W as compared to that of Ta or Pt, which is consistent with the values reported in the literature421222930. Given that the SMR is proportional to the square of spin Hall angle9, the relative magnitude of the SMR indicates that the spin Hall angle of W is approximately three (two) times larger than that of the sample with Ta (Pt).

Bottom Line: This implies the existence of an inverse effect, in which the conductivity in such structures should depend on the magnetization orientation.We observe that the MR is independent of the angle between the magnetization and current direction but is determined by the relative magnetization orientation with respect to the spin direction accumulated by the spin Hall effect, for which the symmetry is identical to that of so-called the spin Hall magnetoresistance.The MR of ~1% in W/CoFeB/MgO samples is considerably larger than those in other structures of Ta/CoFeB/MgO or Pt/Co/AlOx, which indicates a larger spin Hall angle of W.

View Article: PubMed Central - PubMed

Affiliation: Department of Materials Science and Engineering, KAIST, Daejeon 305-701, Korea.

ABSTRACT
The phenomena based on spin-orbit interaction in heavy metal/ferromagnet/oxide structures have been investigated extensively due to their applicability to the manipulation of the magnetization direction via the in-plane current. This implies the existence of an inverse effect, in which the conductivity in such structures should depend on the magnetization orientation. In this work, we report a systematic study of the magnetoresistance (MR) of W/CoFeB/MgO structures and its correlation with the current-induced torque to the magnetization. We observe that the MR is independent of the angle between the magnetization and current direction but is determined by the relative magnetization orientation with respect to the spin direction accumulated by the spin Hall effect, for which the symmetry is identical to that of so-called the spin Hall magnetoresistance. The MR of ~1% in W/CoFeB/MgO samples is considerably larger than those in other structures of Ta/CoFeB/MgO or Pt/Co/AlOx, which indicates a larger spin Hall angle of W. Moreover, the similar W thickness dependence of the MR and the current-induced magnetization switching efficiency demonstrates that MR in a non-magnet/ferromagnet structure can be utilized to understand other closely correlated spin-orbit coupling effects such as the inverse spin Hall effect or the spin-orbit spin transfer torques.

No MeSH data available.


Related in: MedlinePlus