Spin-Orbit Torque in Magnetic Bilayers - Spintronics Theory Group
Spin-Orbit Torque in Magnetic Bilayers - Spintronics Theory Group Spin-Orbit Torque in Magnetic Bilayers - Spintronics Theory Group
I. Spin-‐orbit Coupling Strikes Back b. A new hope… J. Slonczewski L. Berger J. C. Slonczewski, J. Magn. Magn. Mater. 159, L1 (1996). L. Berger, Phys. Rev. B 54, 9353 (1996). AlOx, MgO, TaN Transfer of the spin angular momentum Need a polarizer and a free layer J. Hayakawa, JJAP 44, L1267 (2005) Co, NiFe, CoFeB Pt, Ta, Bi , W Possible Strategies Spin Hall effect in the Heavy Metal: spin current injecOon Miron et al., Nature Materials 2010, 2011, Pi et al., APL 2010; Suzuki et al., APL 2011 Liu et al, PRL 2011, PRL 2012, Science 2012 Kim et al., Nature Materials 2012 J z s ∝ y ⇒ T = J z s Miron Nature 2011 Liu et al., PRL 2011 Liu Science 2012 ∝ m × ( y × m ) HM /F Rashba effect at the Heavy Metal/Ferromagnet interface: spin density generaOon S ∝ y ⇒ T = Δm × S ∝ y × m z y x 10
I. Spin-‐orbit Coupling Strikes Back b. A new hope… Single Domain Measurements Methods: GHz spin-‐FMR, kHz modulaOon Removes effects that depends on texture Domain Wall Measurements Methods: Current-‐induced MoOon Averages the (SO, STT, Damping) torques Anatomy of Spin-‐Orbit Torques ˆT = T ⊥ ( θ) ˆm × ŷ +T || ( θ) ˆm × ( ŷ × ˆm ) Miron, Nature Materials 2010, Nature 2011 Pi, APL 2010; Suzuki, APL 2011 Liu PRL 2011, PRL 2012, Science 2012; Fan Nat. Com. 2013 Kim, Nature Materials 2012, Garello Nature Nano 2013 New effects Reversed moCon (against electron flow) Domain wall distorCon and ClCng Complex Current dependence Miron, Nature Materials 2011 Emori, Nature Materials 2013 Ryu, Nature Nanotechnology 2013 Haazen, Nature Materials 2013 11
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- Page 5 and 6: 1 st International Workshop on Spin
- Page 7 and 8: Outline I. Spin-‐Orbit Coupli
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- Page 15 and 16: II. What the spin is going on
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I. <strong>Sp<strong>in</strong></strong>-‐orbit Coupl<strong>in</strong>g Strikes Back <br />
b. A new hope… <br />
J. Slonczewski <br />
L. Berger <br />
J. C. Slonczewski, J. Magn. Magn. Mater. 159, L1 (1996). <br />
L. Berger, Phys. Rev. B 54, 9353 (1996). <br />
AlOx, MgO, TaN <br />
Transfer of the sp<strong>in</strong> angular momentum <br />
Need a polarizer and a free layer <br />
J. Hayakawa, JJAP 44, L1267 (2005) <br />
Co, NiFe, CoFeB <br />
Pt, Ta, Bi , W <br />
Possible Strategies <br />
<strong>Sp<strong>in</strong></strong> Hall effect <strong>in</strong> the Heavy Metal: sp<strong>in</strong> current <strong>in</strong>jecOon <br />
Miron et al., Nature Materials 2010, 2011, <br />
Pi et al., APL 2010; Suzuki et al., APL 2011 <br />
Liu et al, PRL 2011, PRL 2012, Science 2012 <br />
Kim et al., Nature Materials 2012 <br />
<br />
J z s ∝ y ⇒ T = J z<br />
s<br />
Miron Nature 2011 Liu et al., PRL 2011 Liu Science 2012 <br />
∝ m × ( y × m<br />
)<br />
HM /F<br />
Rashba effect at the Heavy Metal/Ferromagnet <strong>in</strong>terface: sp<strong>in</strong> density generaOon <br />
<br />
S ∝ y ⇒ T = Δm × S ∝ y × m<br />
<br />
z <br />
y <br />
x <br />
10
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