Hiroyuki Inoue

1. Electric manipulation of spin relaxation in a film using spin-Hall effect K. Ando et al (PRL in press) Hiroyuki Inoue

2. Why Spintronics? A Relativistic View

3. Relativity says Duality of Electricity and Magnetism E ↔ B P ↔ M

4. P P’ v M’

5. M M’ v P’

6. Wilson’s experiment (1913) V P rotating magnetization Inducing electromotiveforce (EMF) (electric polarization P) v (jc) S Ｍ N

7. Fundamental Purposes of Spintronics electricity → electric charge ρe electric current → charge current Jc magnetism → magnetic charge (dipole) ρm magnetic dipole current → spin current Js Harness the duality of Electricity and Magnetism E, P charge B, M spin

8. Introduction of Spin Current opens a New Perspective to Magnetic Phenomena

9. A Wise Saying (!?) by Yehoshua Ah? What is spin current? Whydo we need to think about spin current? OK, then, I will go to a market. and I will buy a banana current! Spin current is not that stupid thing to think about…

10. Current of Electrons in Solids up-spin current down-spin current J↑ μ↓ J↓ μ↑ x x

11. Electric Current & Spin Current charge current and spin current charge spin Jc = J↑ + J↓ e v = Charge Current Js = J↑ - J↓ σ v = Spin Current

12. Phenomenological Description of Magnetization Dynamics Heff Landau-Lifshitz-Gilbert equation D Magnetization damping term -M×H Dissipation of angular momentum M Transferred to conduction electrons Generation of spin current (μ↑≠μ↓) Magnetization Relaxation = Production of Spin Current

13. Driving Magnetization Precession Generates Spin Current Supply angular momentum by EMW EM Heff σ Balance of emission and absorption of angular momentum D v -M×Heff Maintain magnetization-precession M Ferromagnetic Resonance Continuous operation of spin pumping Ferromagnetic Resonance = Continuous Generation of Spin Current

14. Experiments

15. Spin Hall Effect intrinsic: Band Berry Phase Spin-Orbit interaction (relativistic effect) extrinsic: Impurity Scattering -e JS JS Jc Jc -e -e Spin-Hall effect Inverse spin-Hall effect 1. Zhang et al. PRL (2000) 2. Murakami et al. science (2003) 3. Sinova et al. PRL (2004) 4. Kimura et al. JMMM (2004) 5. Kato et al. science (2004) 6. Wunderlich et al. PRL (2005) 7. Ueda et al. APL(2006)

16. Experimental Setup V,I Ni81 Fe19 (10 nm)(FM) Pt (10 nm)(NM) EMW SiO2 substrate HMW H Sweep & Lock-in TE011 microwave cavity derivative of Lorentzian function

17. Pt layer Enhances Relaxation of Magnetization Ni81Fe19 Pt J↑ μ↑ μ↓ J↓ Enhancement of M relaxation

18. Spin Current Injection Indeed Yields EMF -e JS 10-3 V/T -e Jc EMF due to ISHE ( Js → Jc) = ( M → P ) Lorentz transformation in a solid H. Inoue, K. Ando et al. (J. Appl. Phys)

19. Inverse Process Realizes Electrical Manipulation of M-relaxation I δM⊥ spin torque D spin torque ( Jc → Js ) = ( P → M ) Spin-Hall effect: spin current injection to Ni81Fe19 layer M spin torque manipulates the damping term

20. direction of current: direction of polarization of spin current current intensity: amount of spin torque modulation of M-relaxation asscociated with the current-directional reversal

21. electrical manipulation of magnetization relaxation conventionally, difficult to achieve after once material species, temperature, and pressure are given this scheme is applicable for spin-current meter

22. Main Points to Remember Spin current introduces new perspectives to magnetic phenomena which harness the duality of electricity and magnetism. They realized electric manipulation of magnetization relaxation, which can be also applied to spin-current meter.

24. magnetic monopoles can exist in solids… S S N

25. Josephson Effect of Charge and Spin superconductor ferromagnet θ θ’ M M’ jsi≈∂iθ jssi≈M×∂iM Super charge current Super spin current

26. Deduction of Super Spin Current A

27. Deduction of Super Spin Current Electric current Charge density ChargeContinuity Equation Spin Continuity Equation Super Spin Current