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Spin Torque Transfer Technology S. James Allen UC Santa Barbara • Science • Technology Spin Torque Transfer – RAM, STT-RAM Spin Torque Transfer Nano-oscillators Spin logic devices ITRS Emerging Technology Review, 12 July 2008 1 Contact: SJ Allen, [email protected] Spin Torque Transfer Technology With input from Mark Rodwell Bob Buhrman Stu Wolf H. Ohno Nick Rizzo Yiming Huai Bill Rippard Steve Russek Eli Yablonovitch Ajey Jacob ITRS Emerging Technology Review, 12 July 2008 UC Santa Barbara Cornell U. Virginia Tohoku University Free Scale Grandis NIST NIST UC Berkeley Intel 2 Contact: SJ Allen, [email protected] Spin Torque Transfer Technology From R. A. Buhrman, “Spin Torque Effects in Magnetic Nanostructures”, Spintech IV, 2007 • Science • Technology Spin Torque Transfer – RAM, STT-RAM Spin Torque Transfer Nano-oscillators Spin logic devices ITRS Emerging Technology Review, 12 July 2008 3 Contact: SJ Allen, [email protected] Spin Torque Transfer: Science J. C. Slonczewski, “Conductance and exchange coupling of two ferromagnets separated by a tunneling barrier”, Phys. Rev. B, 39 6995 (1989). • Heisenberg exchange • Giant magneto resistance • Spin transfer torque ITRS Emerging Technology Review, 12 July 2008 4 Contact: SJ Allen, [email protected] Spin Torque Transfer: Science Ferromagnet Non-magnetic J. C. Slonczewski, “Conductance and exchange coupling of two ferromagnets separated by a tunneling barrier”, Phys. Rev. B, 39 6995 (1989). Ef , 1-band Ferromagnet • Heisenberg exchange • Giant magneto resistance • Spin transfer torque ITRS Emerging Technology Review, 12 July 2008 5 Contact: SJ Allen, [email protected] Spin Torque Transfer: Science J. C. Slonczewski, “Conductance and exchange coupling of two ferromagnets separated by a tunneling barrier”, Phys. Rev. B, 39 6995 (1989). Ferromagnet Ef , 1-band Ferromagnet Ferromagnetic Ferromagnetic Anti-ferromagnetic Anti-ferromagnetic • Heisenberg exchange ITRS Emerging Technology Review, 12 July 2008 6 Contact: SJ Allen, [email protected] Spin Torque Transfer: Science J. C. Slonczewski, “Conductance and exchange coupling of two ferromagnets separated by a tunneling barrier”, Phys. Rev. B, 39 6995 (1989). Ef , 1-band I / V G G0 ( R R(0)) 1 P 2 cos R 0 (1 P 2 ) • Giant magneto resistance ITRS Emerging Technology Review, 12 July 2008 7 2P 2 (1 P 2 ) P = 1, ideal, perfect spin valve Contact: SJ Allen, [email protected] H. Ohno, “Spintronics” Seminar, UCSB May, 2008 ITRS Emerging Technology Review, 12 July 2008 8 Contact: SJ Allen, [email protected] H. Ohno, “Spintronics” Seminar, UCSB May, 2008 ( R R(0)) R 0 2P 2 6 2 (1 P ) P 0.87 P = 1, ideal, perfect spin valve ITRS Emerging Technology Review, 12 July 2008 9 Contact: SJ Allen, [email protected] H. Ohno, “Spintronics” Seminar, UCSB May, 2008 Free M. Hosomi, et al., “A novel nonvolatile memory with spin torque transfer magnetization switching: spin-ram”, Electron Devices Meeting,2005. IEDM Technical Digest. IEEE International, pp. 459-462. Fixed SyF P 0.6 P = 1, ideal, perfect spin valve ITRS Emerging Technology Review, 12 July 2008 10 Contact: SJ Allen, [email protected] Spin Torque Transfer: Science J. C. Slonczewski, “Conductance and exchange coupling of two ferromagnets separated by a tunneling barrier”, Phys. Rev. B, 39 6995 (1989). dm dt Free dm o m H A dt m dm dt Effective field Damping • Spin transfer torque ITRS Emerging Technology Review, 12 July 2008 11 Contact: SJ Allen, [email protected] Spin Torque Transfer: Science J. C. Slonczewski, “Conductance and exchange coupling of two ferromagnets separated by a tunneling barrier”, Phys. Rev. B, 39 6995 (1989). dm dt dm dt Free dm o m H A dt Effective field Fixed J e m dm dt Damping B J / e P t MS B J / e P t MS m p m m p Slonczewski torque Effective magnetic field • Spin transfer torque ITRS Emerging Technology Review, 12 July 2008 12 Contact: SJ Allen, [email protected] Spin Torque Transfer: Science J. C. Slonczewski, “Conductance and exchange coupling of two ferromagnets separated by a tunneling barrier”, Phys. Rev. B, 39 6995 (1989). dm J dt • Precession • Switching • Damping dm dt dm dt Free dm o m H A dt m Fixed - J e • Spin transfer torque ITRS Emerging Technology Review, 12 July 2008 Effective field dm dt Damping B J / e P t MS B J / e P t MS 13 m p m m p Slonczewski torque Effective magnetic field Contact: SJ Allen, [email protected] Spin Torque Transfer Technology From R. A. Buhrman, “Spin Torque Effects in Magnetic Nanostructures”, Spintech IV, 2007 • Science • Technology Spin Torque Transfer – RAM, STT-RAM Spin Torque Transfer Nano-oscillators Spin logic devices ITRS Emerging Technology Review, 12 July 2008 14 Contact: SJ Allen, [email protected] GMR and STT --- STT-RAM J. C. Slonczewski, “Conductance and exchange coupling of two ferromagnets separated by a tunneling barrier”, Phys. Rev. B, 39 6995 (1989). dm J dt • Precession • Switching • Damping dm dt dm dt Free dm o m H A dt m Fixed - J e • Spin transfer torque ITRS Emerging Technology Review, 12 July 2008 Effective field dm dt Damping B J / e P t MS B J / e P t MS 15 m p m m p Slonczewski torque Effective magnetic field Contact: SJ Allen, [email protected] GMR and STT --- STT-RAM T. Kawahara, R. Takemura, K. Miura, J. Hayakawa, S. Ikeda, Y.M. Lee, R. Sasaki, Y. Gotot, K. Ito, T. Meguro, F. Matskura, H. Takahash, H. Matsuoka and H. Ohno, “2 Mb SPRAM (Spin-Transfer Torque RAM) with bit-by-bit bi-directional current write and parallelizing-direction current read”, IEEE J Solid-State Circuits, 43, 109 (2008). ~ 200 A ITRS Emerging Technology Review, 12 July 2008 16 Contact: SJ Allen, [email protected] Conventional MRAM (toggle) and Spin Torque MRAM Spin polarized current produces torque to reverse free layer. H field produces torque to reverse free layer. •Isw < 1 mA/bit for 0.06 m x 0.12 m bit. •Isw reduces as bit scales smaller. •Need Isw ≈ 40 mA/bit for 0.4 um x 1.0 um. •Isw constant for smaller bits. ITRS Emerging Technology Review, 12 July 2008 17 Contact: SJ Allen, [email protected] STT-RAM 2005 Free Fixed SyF M. Hosomi, H. Yamagishi, T. Yamamoto, K. Bessho, Y. Higo, K. Yamane, H. Yamada, M. Shoji, H. Hachino, C. Fukumoto, H. Nagao, H. Kano, “A novel nonvolatile memory with spin torque transfer magnetization switching: spin-ram”, Electron Devices Meeting,2005. IEDM Technical Digest. IEEE International, pp. 459462. ITRS Emerging Technology Review, 12 July 2008 18 Contact: SJ Allen, [email protected] STT-RAM 2005 M. Hosomi, H. Yamagishi, T. Yamamoto, K. Bessho, Y. Higo, K. Yamane, H. Yamada, M. Shoji, H. Hachino, C. Fukumoto, H. Nagao, H. Kano, “A novel nonvolatile memory with spin torque transfer magnetization switching: spin-ram”, Electron Devices Meeting,2005. IEDM Technical Digest. IEEE International, pp. 459462. CMOS driver 100 A/100 nm S. Ikeda, J.Hayakawa, Y.M. Lee, F. Matsukura, Y. Ohno, T. Hanyu and H. Ohno, “Magnetic tunnel junctions for spintronic memories and beyond”, IEEE Trans Elec. Dev. 54, 991 (2007). ITRS Emerging Technology Review, 12 July 2008 19 Contact: SJ Allen, [email protected] STT-RAM 2005 Read ~ 0.2 V < write! M. Hosomi, H. Yamagishi, T. Yamamoto, K. Bessho, Y. Higo, K. Yamane, H. Yamada, M. Shoji, H. Hachino, C. Fukumoto, H. Nagao, H. Kano, “A novel nonvolatile memory with spin torque transfer magnetization switching: spin-ram”, Electron Devices Meeting,2005. IEDM Technical Digest. IEEE International, pp. 459462. CMOS sensing > 0.2 V S. Ikeda, J.Hayakawa, Y.M. Lee, F. Matsukura, Y. Ohno, T. Hanyu and H. Ohno, “Magnetic tunnel junctions for spintronic memories and beyond”, IEEE Trans Elec. Dev. 54, 991 (2007). ITRS Emerging Technology Review, 12 July 2008 20 Contact: SJ Allen, [email protected] STT-RAM 2005 Sony 4 kb M. Hosomi, H. Yamagishi, T. Yamamoto, K. Bessho, Y. Higo, K. Yamane, H. Yamada, M. Shoji, H. Hachino, C. Fukumoto, H. Nagao, H. Kano, “A novel nonvolatile memory with spin torque transfer magnetization switching: spin-ram”, Electron Devices Meeting,2005. IEDM Technical Digest. IEEE International, pp. 459462. S. Ikeda, J.Hayakawa, Y.M. Lee, F. Matsukura, Y. Ohno, T. Hanyu and H. Ohno, “Magnetic tunnel junctions for spintronic memories and beyond”, IEEE Trans Elec. Dev. 54, 991 (2007). ITRS Emerging Technology Review, 12 July 2008 21 Contact: SJ Allen, [email protected] STT-RAM 2007 115 x 180 nm2 Grandis, Inc. STT-RAM cell with integrated CMOS transistor. The area of a single-level STTRAM cell can be as small as 6 F2. Y. Huai, Z. Diao, Y.Ding, A. Panchula, S. Wang, Z. Li, D. Apalkov, X. Luo, H. Nagai, A. Driskill-Smith, and E. Chen, “Spin Transfer Torque RAM (STTRAM) Technology”, 2007 Inter. Conf. Solid State Devices and Materials, Tsukuba, 2007, pp. 742-743. S. Ikeda, J.Hayakawa, Y.M. Lee, F. Matsukura, Y. Ohno, T. Hanyu and H. Ohno, “Magnetic tunnel junctions for spintronic memories and beyond”, IEEE Trans Elec. Dev. 54, 991 (2007). Courtesy of Yiming Huai ITRS Emerging Technology Review, 12 July 2008 22 Contact: SJ Allen, [email protected] STT-RAM 2007 Hitachi T. Kawahara, R. Takemura, K. Miura, J. Hayakawa, S. Ikeda, Y.M. Lee, R. Sasaki, Y. Gotot, K. Ito, T. Meguro, F. Matskura, H. Takahash, H. Matsuoka and H. Ohno, “2 Mb SPRAM (Spin-Transfer Torque RAM) with bit-by-bit bi-directional current write and parallelizing-direction current read”, IEEE J Solid-State Circuits, 43, 109 (2008). S. Ikeda, J.Hayakawa, Y.M. Lee, F. Matsukura, Y. Ohno, T. Hanyu and H. Ohno, “Magnetic tunnel junctions for spintronic memories and beyond”, IEEE Trans Elec. Dev. 54, 991 (2007). Courtesy of Hideo Ohno ITRS Emerging Technology Review, 12 July 2008 23 Contact: SJ Allen, [email protected] GMR and STT --- STT-RAM T. Kawahara, R. Takemura, K. Miura, J. Hayakawa, S. Ikeda, Y.M. Lee, R. Sasaki, Y. Gotot, K. Ito, T. Meguro, F. Matskura, H. Takahash, H. Matsuoka and H. Ohno, “2 Mb SPRAM (Spin-Transfer Torque RAM) with bit-by-bit bi-directional current write and parallelizing-direction current read”, IEEE J Solid-State Circuits, 43, 109 (2008). ITRS Emerging Technology Review, 12 July 2008 24 Contact: SJ Allen, [email protected] STT-RAM Projections vs State-of-the-art A.Driskill-Smith, Y. Huai, “STT-RAM – A New Spin on Universal Memory”, Future Fab, 23, 28 Hitachi, 2007 Yes 1.6 x 1.6 m TMR 100 x 50 nm2 (60) 40 ns 100 ns > 109 40 pJ/100ns None 1.8 V T. Kawahara, R. Takemura, K. Miura, J. Hayakawa, S. Ikeda, Y.M. Lee, R. Sasaki, Y. Gotot, K. Ito, T. Meguro, F. Matskura, H. Takahash, H. Matsuoka and H. Ohno, “2 Mb SPRAM (Spin-Transfer Torque RAM) with bit-by-bit bi-directional current write and parallelizing-direction current read”, IEEE J Solid-State Circuits, 43, 109 (2008). ITRS Emerging Technology Review, 12 July 2008 25 Contact: SJ Allen, [email protected] STT-RAM Projections vs State-of-the-art Nick Rizzo, Freescale Toggle MRAM (180 nm) Toggle MRAM (90 nm)* DRAM (90 nm)+ SRAM (90 nm)+ FLASH (90 nm)+ FLASH (32 nm)+ ST MRAM (90 nm)* ST MRAM (32 nm)* cell size (m2) 1.25 0.25 0.05 1.3 0.06 0.01 0.06 0.01 Read time 35 ns 10 ns 10 ns 1.1 ns 10 - 50 ns 10 - 50 ns 10 ns 1 ns 40 ns Program time 5 ns 5 ns 10 ns 1.1 ns 0.1-100 ms 0.1-100 ms 10 ns 1 ns 100 ns Program energy/bit 150 pJ 120 pJ 5 pJ Needs refresh 5 pJ 30 – 120 nJ 10 nJ 0.4 pJ 0.04 pJ 40 pJ Endurance > 1015 > 1015 > 1015 > 1015 > 1015 read, > 106 write > 1015 read, > 106 write > 1015 >1015 > 109 Nonvolatility YES YES NO NO YES YES YES YES Yes 1.6 x 1.6 m TMR 100 x 50 nm2 (60) T. Kawahara, R. Takemura, K. Miura, J. Hayakawa, S. Ikeda, Y.M. Lee, R. Sasaki, Y. Gotot, K. Ito, T. Meguro, F. Matskura, H. Takahash, H. Matsuoka and H. Ohno, “2 Mb SPRAM (Spin-Transfer Torque RAM) with bit-by-bit bi-directional current write and parallelizing-direction current read”, IEEE J Solid-State Circuits, 43, 109 (2008). * 90nm, 32nm MRAM values are projected + These values are from the ITRS roadmap ITRS Emerging Technology Review, 12 July 2008 Hitachi, 2007 26 Contact: SJ Allen, [email protected] Information Requested (2/2) STT - RAM • • • Current state-of-the-art using the provided metrics as a guide (Appendix 2 of request for white papers) CMOS integrated STT-RAM demonstrated. 2Mb Key scientific and technological issues remaining to accept the technology for manufacture. Lower critical currents and larger TMR ratio. Quality of the tunnel junction is critical. Technology roadmap outlining a 5-15 year develop path leading to manufacture in 5-10 years. Replace MRAM. Embedded memory in logic applications. Longer term – universal memory. ITRS Emerging Technology Review, 12 July 2008 27 Contact: SJ Allen, [email protected] Spin Transfer Torque Nano-oscillator J. C. Slonczewski, “Conductance and exchange coupling of two ferromagnets separated by a tunneling barrier”, Phys. Rev. B, 39 6995 (1989). dm J dt • Precession • Switching • Damping dm dt dm dt Free dm o m H A dt m Fixed - J e • Spin transfer torque ITRS Emerging Technology Review, 12 July 2008 Effective field dm dt Damping B J / e P t MS B J / e P t MS 28 m p m m p Slonczewski torque Effective magnetic field Contact: SJ Allen, [email protected] Spin Transfer Torque Nano-oscillator S. I. Kiselev, J. C. Sankey, I. N. Krivorotov, N. C. Emley, R. J. Schoelkopf, R. A. Buhrman and D. C. Ralph, “Microwave oscillations of a nanomagnet driven by a spin-polarized current”, Nature, 425,380 (2003).“ 30 nmPt 2 nm Cu/ 3 nm Co/ 10 nm Cu/ 40 nmCo/ 80 nm Cu/ ~ 0.1 nW measured H 130 x 70 nm2 ITRS Emerging Technology Review, 12 July 2008 29 Contact: SJ Allen, [email protected] Spin Transfer Torque Nano-oscillator S. I. Kiselev, J. C. Sankey, I. N. Krivorotov, N. C. Emley, R. J. Schoelkopf, R. A. Buhrman and D. C. Ralph, “Microwave oscillations of a nanomagnet driven by a spin-polarized current”, Nature, 425,380 (2003).“ 30 nmPt 2 nm Cu/ 3 nm Co/ 10 nm Cu/ 40 nmCo/ 80 nm Cu/ ~ 0.1 nW measured H 130 x 70 nm2 Key element: A skew magnetic field ! ITRS Emerging Technology Review, 12 July 2008 30 Contact: SJ Allen, [email protected] Spin Transfer Torque Nano-oscillator ~ 0.1 nW measured 30 nmPt 2 nm Cu/ 3 nm Co/ 10 nm Cu/ 40 nmCo/ 80 nm Cu/ H 130 x 70 nm2 Cu junction R 13 R 0.1 I DC 2.0 mA ITRS Emerging Technology Review, 12 July 2008 2 Pmax 2 11 50 1 I DC R 2 2 R 50 50 ~ 0.2 nW estimated max. Efficiency 31 10 6 Contact: SJ Allen, [email protected] Spin Transfer Torque Nano-oscillator: Injection Locking W. H. Rippard, M. R. Pufall, S. Kaka, T. J. Silva, S. E. Russek, J. A. Katine, “Injection Locking and Phase Control of Spin Transfer Nano-oscillators”, Phys. Rev. Lett., 95, 067203 (2005). 1 nm Au 1 nm Cu/ 5 nm NiFe/ 4 nm Cu/ 20 nm CoFe/ 50 nmCu/ 5 nm Ta/ ~ 30 pW 50 x 50 nm2 0.56 Tesla ITRS Emerging Technology Review, 12 July 2008 32 Contact: SJ Allen, [email protected] Spin Transfer Torque Nano-oscillator: Frequency Modulation M. R. Pufall, W. H. Rippard, S. Kaka, T. J. Silva, and S. E. Russek “Frequency modulation of spin-transfer oscillators” Appl. Phys. Lett. 86, 082506 (2005). ~ 250 pW ITRS Emerging Technology Review, 12 July 2008 33 Contact: SJ Allen, [email protected] Spin Transfer Torque Nano-oscillator: Phase Locking S. Kaka, M.R. Pufall, W.H. Rippard, T.J. Silva, S.E. Russek and J.A. Katine, “Mutual phase-locking of microwave spin torque nanooscillators” Nature, 437, 389 (2005). ITRS Emerging Technology Review, 12 July 2008 34 ~ 2 pW Contact: SJ Allen, [email protected] Spin Transfer Torque Nano-oscillator: B=0.0 dm o m H A Effective field, shape, material dt J / e P B m p m Slonczewski torque t MS dm dt B J / e P m p t MS m T. Devoldera, A. Meftah, K. Ito, J. A. Katine, P. Crozat and C. Chappert, “Spin transfer oscillators emitting microwave in zero applied magnetic field”, J. Appl. Phys. 101, 063916 2007. < 1.0 pW Damping Effective magnetic field 0.05 Fixed layer Free ITRS Emerging Technology Review, 12 July 2008 35 Contact: SJ Allen, [email protected] Spin Transfer Torque Nano-oscillator: Power issues? Some measures: Cell phone – 900 MHz, 1.8GHz, ~ 500 mW Wireless access points – 2.4 GHz, 5.0 GHz, ~ 25 mW Automotive radar 24 GHz, 100 GHz ~ 10 mW State of the art STT nano-oscillators External magnetic field, ITRS Emerging Technology Review, 12 July 2008 36 ~ nW, efficiency 10-6 Contact: SJ Allen, [email protected] Spin Transfer Torque Nano-oscillator 30 nmPt 2 nm Cu/ 3 nm Co/ 10 nm Cu/ 40 nmCo/ 80 nm Cu/ MgO tunnel barrier R 100 R 100 I DC 1 mA MgO tunnel barrier 2 Cu junction R 13 R 0.1 I DC 2.0 mA ITRS Emerging Technology Review, 12 July 2008 Pmax 2 11 50 1 I DC R 2 2 R 50 50 ~ 1 W estimated Efficiency 37 10 2 Contact: SJ Allen, [email protected] Spin Transfer Torque Nano-oscillator: Power issues? Some measures: Cell phone – 900 MHz, 1.8GHz, ~ 500 mW Wireless access points – 2.4 GHz, 5.0 GHz, ~ 25 mW Automotive radar 24 GHz, 100 GHz ~ 10 mW State of the art STT nano-oscillators External magnetic field, ~ nW, efficiency ~ 10-6 Projection MTJ based STT nano-oscillators ~ W, efficiency ~ 10-2 ? Power combining ? But touch base with the Cornell, NIST, UVa collaboration ITRS Emerging Technology Review, 12 July 2008 38 Contact: SJ Allen, [email protected] Information Requested (2/2) STT Nano-oscillators • • • Current state-of-the-art using the provided metrics as a guide (Appendix 2 of request for white papers) Nano-oscillators at the nano-picowatt level with spin valve structures, in external magnetic fields. Existence proof of approach to external magnetic field free sustained oscillation. Phase locking, frequency modulation, injection locking demonstrated. Key scientific and technological issues remaining to accept the technology for manufacture. Increased power. Use of magnetic tunnel junctions. Power combining. Technology roadmap outlining a 5-15 year develop path leading to manufacture in 5-10 years. Needs to be guided by potential applications. ITRS Emerging Technology Review, 12 July 2008 39 Contact: SJ Allen, [email protected] “MRAM” --- Spin Logic Device • Current controlled • Non-volatile R ~6 • “Leaky” switch, Mark Rodwell, UC Santa Barbara High R R Isignal Gate Current Gate Insulator B Field Source Ru 15nm I B Field Ta 5nm Ferromagnetic CoFeB 3nm Magnetization MgO 1.5nm Tunnel Barrier Eli Yablonovitch, UC Berkeley Ferromagnetic CoFeB 3nm Ru 0.8nm CoFe 2nm Antiferromagnetic MnIr 8nm I source “transpinnor” NiFe 5nm Ta 5nm Ru 50nm Drain R Ta 5nm Si (001) Substrate Device Area 1?m2 drain Ikeda et. al., Japanese Journal of Applied Physics, Vol. 44, No 48, pp. L1442-L1445 I ITRS Emerging Technology Review, 12 July 2008 40 Contact: SJ Allen, [email protected] Two views - Spin Logic Output Power = 1.6*10-8 W Total Power = 2.5*10-8 W Efficiency=65% R High Eli Yablonovitch +V +3mV I Mark Rodwell 2.275kΩ or 500Ω 5μA input Iss 5μA output Iinput Iss input Ioutput Inverter Complementary Transpinnor logic Ioutput output High High -V -3mV Iss •Problems: On/Off ratio is only about 5:1 Still takes too many Amps to switch ITRS Emerging Technology Review, 12 July 2008 Iss High High 500Ω or 2.275kΩ Iinput 41 Three state circuits • memory and logic • clocked logic • “0” static dissipation Contact: SJ Allen, [email protected] “MRAM” --- Spin Logic Device • Current controlled • Non-volatile R ~6 • “Leaky” switch, Mark Rodwell, UC Santa Barbara High R R Isignal Gate Current Gate Insulator B Field Source Ru 15nm I B Field Ta 5nm Ferromagnetic CoFeB 3nm Magnetization MgO 1.5nm Tunnel Barrier Eli Yablonovitch, UC Berkeley Ferromagnetic CoFeB 3nm Ru 0.8nm CoFe 2nm Antiferromagnetic MnIr 8nm I source “transpinnor” NiFe 5nm Ta 5nm Ru 50nm Drain R Ta 5nm Si (001) Substrate Device Area 1?m2 drain Ikeda et. al., Japanese Journal of Applied Physics, Vol. 44, No 48, pp. L1442-L1445 I ITRS Emerging Technology Review, 12 July 2008 42 Contact: SJ Allen, [email protected] GMR and STT --- Spin Logic Device? Can we control GMR by Magnetostatically coupling to a STT switch ?? Mark Rodwell, UC Santa Barbara High R GMR – “switch” STT – “switch control” I Eli Yablonovitch, UC Berkeley I source “transpinnor” Contact Fixed R Contact drain Contact I ITRS Emerging Technology Review, 12 July 2008 Contact Magnetostatically coupled free layers 43 Contact: SJ Allen, [email protected] GMR and STT --- Spin Logic Device? Can we control GMR by Magnetostatically coupling to a STT switch ?? GMR – “switch” Contact O. Ozatay,a_ N. C. Emley, P. M. Braganca, A. G. F. Garcia, G. D. Fuchs, I. N. Krivorotov,R. A. Buhrman, and D. C. Ralph, “Spin transfer by nonuniform current injection into a nanomagnet”, Appl. Phys. Lett., 88, 202502 (2006). STT – “switch control” Contact Fixed Contact Contact Magnetostatically coupled free layers ITRS Emerging Technology Review, 12 July 2008 44 Contact: SJ Allen, [email protected] GMR and STT --- Spin Logic Device? Input Current driven Clocked logic Inherent memory, ISS → 0, no change in input of next stage Output ISS Iss input ISS High High output High High M. Rodwell Inverter Output Iss ITRS Emerging Technology Review, 12 July 2008 45 Input Contact: SJ Allen, [email protected] GMR and STT --- Spin Logic Device? O utput A Input IS S B Input M. Rodwell NAND Current controlled Clocked logic 3-state, nonvolatile F IS S Cell 100F2 Energy per bit ~ 4* STT-RAM Switching speed slower than STT-RAM Input Input O utput ITRS Emerging Technology Review, 12 July 2008 46 Contact: SJ Allen, [email protected] Information Requested (2/2) GMR-STT Spin logic devices • Current state-of-the-art using the provided metrics as a guide (Appendix 2 of request for white papers) “Straw man” concepts, synergistic with STT-RAM developments • Key scientific and technological issues remaining to accept the technology for manufacture. Demonstration of magneto-static proximity coupling of GMR device and STT switch • Technology roadmap outlining a 5-15 year develop path leading to manufacture in 5-10 years. Premature ITRS Emerging Technology Review, 12 July 2008 47 Contact: SJ Allen, [email protected] Spin Torque Transfer Technology A perspective: STT-RAM will be developed for memory embedded in logic applications. STT Nano-oscillators development needs to guided by potential application. Research on potential STT Logic will be leveraged by developments in STT-RAM ITRS Emerging Technology Review, 12 July 2008 48 Contact: SJ Allen, [email protected]