Spin Valves by Quantum Mechanics Thomas Prevenslik QED

Spin. Valves by Quantum Mechanics Thomas Prevenslik QED Radiations Discovery Bay, Hong Kong 1 NANOSMAT-Asia : Inter. Conf. Surf. , Coat. , Nano-Materials; Wuhan, CHINA, Mar. 13 -15, 2013

Introduction Spin. Valve ferromagnetism is based on theoretical predictions by Slonczewski and Berger a decade ago. Spin. Valves comprise alternating nanoscale layers of FMs separated by a NM spacer. FM stands for ferromagnetic and NM for non-magnetic. Spin-polarized current is produced by passing un-polarized current through a first FM layer, the polarization unchanged as the current flows through the NM spacer. In the second FM layer, a giant magneto-resistance (GMR) is thought to transfer the spin angular momentum as a physical spin-torque, the process tending to produce parallel spins that significantly lower the GMR. 2 NANOSMAT-Asia : Inter. Conf. Surf. , Coat. , Nano-Materials; Wuhan, CHINA, Mar. 13 -15, 2013

Problems The significant reduction in the GMR by the alignment of spins is not without controversy. The relatively rigid lattice shields the spins so that any transfer of spin-torque to the second FM is unlikely. Further, spin-torque propagates by phonons through the FM lattices, and therefore limiting spin-transfer to frequencies < 10 GHz having response times > 100 ps. Electron spins observed to respond much faster. 3 NANOSMAT-Asia : Inter. Conf. Surf. , Coat. , Nano-Materials; Wuhan, CHINA, Mar. 13 -15, 2013

Alternatives Laser studies in femtomagnetism by Boeglin et al. show nanoscale FMs demagnetize on a sub-picosecond time scale (< 350 fs) far faster than phonons can respond. Spin transfer through the lattice therefore cannot be the mechanism for demagnetization Bigot et al. showed about 10 ps for the lattice to thermalize prompting Bovensiepen to suggest Spin. Valves de-magnetize by light noting* the dynamics are only observed while the laser field interacts with the FM * Similarity with the EM confinement of a TIR quasi-bound state, trapped in a potential well , but leaking to the outside world by tunneling. NANOSMAT-Asia : Inter. Conf. Surf. , Coat. , Nano-Materials; Wuhan, CHINA, Mar. 13 -15, 2013 4

QED Induced Radiation Provided the RI of the FM is greater than that of the adjacent NM spacers, non-thermal EM radiation at EUV levels is created by the QED induced frequency up-conversion of Joule heat to the TIR confinement frequency of the FM. RI = refractive index. EM = electromagnetic QED = quantum electrodynamics EUV = extreme UV, TIR total internal reflection Excitons (holon and electron pairs) are readily created by the QED induced photoelectric effect. Holons (positive holes) act as charge carriers that significantly reduce the GMR of the FM by a dramatic increase in photoconductivity. 5 NANOSMAT-Asia : Inter. Conf. Surf. , Coat. , Nano-Materials; Wuhan, CHINA, Mar. 13 -15, 2013

Theory Heat Capacity of the Atom Conservation of Energy TIR Confinement 6 NANOSMAT-Asia : Inter. Conf. Surf. , Coat. , Nano-Materials; Wuhan, CHINA, Mar. 13 -15, 2013

Planck Energy - E - e. V Heat Capacity of the Atom 0, 1 Classical Physics (k. T > 0) 0, 01 k. T 0. 0258 e. V QM (k. T = 0) 0, 001 0, 0001 1 E-05 1 10 100 Thermal Wavelength - l - microns Nanostructures In nanostructures, QM requires atoms to have zero heat capacity NANOSMAT-Asia : Inter. Conf. Surf. , Coat. , Nano-Materials; Wuhan, CHINA, Mar. 13 -15, 2013 7

Conservation of Energy Lack of heat capacity by QM precludes Joule heat conservation in nanoelectroncs by an increase in temperature, but how does conservation proceed? Proposal Absorbed EM energy is conserved by creating QED photons inside the nanostructure - by frequency up - conversion to the TIR resonance of the nanostructure. NANOSMAT-Asia : Inter. Conf. Surf. , Coat. , Nano-Materials; Wuhan, CHINA, Mar. 13 -15, 2013 8

TIR Confinement Since the RI of nanoelectroncs is greater than that of the surroundings, the QED photons are confined by TIR corresponding to a quasi-bound state Nanostructures ( films, wires, etc) have high surface to volume ratio, but why important? By QM, the EM energy absorbed in the surface of nanostructures provides TIR confinement of the QED photons are spontaneously created by Joule heat dissipated in nanoelectronics. Simply, f = c/ = 2 nd E = hf NANOSMAT-Asia : Inter. Conf. Surf. , Coat. , Nano-Materials; Wuhan, CHINA, Mar. 13 -15, 2013 9

Electrical Response QED Photons and Excitons Exciton Response Mobility Resistance and Current 10 NANOSMAT-Asia : Inter. Conf. Surf. , Coat. , Nano-Materials; Wuhan, CHINA, Mar. 13 -15, 2013

QED Photons and Excitons QED Photon Rate P = Joule heat E = QED Photon energy = Absorbed Fraction Exciton Rate Y = Yield of Excitons / QED Photon 11 NANOSMAT-Asia : Inter. Conf. Surf. , Coat. , Nano-Materials; Wuhan, CHINA, Mar. 13 -15, 2013

Exciton Response Electrons Holons Where, QE and QH are number electrons and holons, V is the voltage E and H are electron and holon mobility For memristors, V = Vo sin t. For Spin. Valves, Ovshinsky effect , and 1/f Noise, V = Vo, NANOSMAT-Asia : Inter. Conf. Surf. , Coat. , Nano-Materials; Wuhan, CHINA, Mar. 13 -15, 2013 12

Mobility • NANOSMAT-Asia : Inter. Conf. Surf. , Coat. , Nano-Materials; Wuhan, CHINA, Mar. 13 -15, 2013 13

Resistance and Current = Conductivity = Resistivity 14 NANOSMAT-Asia : Inter. Conf. Surf. , Coat. , Nano-Materials; Wuhan, CHINA, Mar. 13 -15, 2013

Applications Spin. Valves Briefly Memristors Ovshinsky Effect 1/f Noise 15 NANOSMAT-Asia : Inter. Conf. Surf. , Coat. , Nano-Materials; Wuhan, CHINA, Mar. 13 -15, 2013

Spin. Valves - Simulation The QED induced switching is simulated for Alq 3 film thicknesses of 10, 20, 50, and 100 nm. All films were assumed to have an initial GMR of Ro = 1 x 106 ohms. A voltage Vo = 1 V was applied for 10 ns followed by Vo = -1 V for 10 ns The QED induced reduction in GMR is significant The 10 nm film resistance ratio R/Ro is reduced to ~ 0. 000624 or (R ~ 624 ohms) in < 1 ns. In contrast, magnetic induced GMR reductions for 125 nm Alq 3 film at 100 K shows a GMR reduction of about 22% corresponding to R/Ro = 0. 78 NANOSMAT-Asia : Inter. Conf. Surf. , Coat. , Nano-Materials; Wuhan, CHINA, Mar. 13 -15, 2013 16

Spin. Valves - Resistance 1 Write Resistance Ratio - R/RO Spin only Erase Vo = + 1 V Vo = -1 V 0, 1 100 nm 0, 01 50 nm 0, 001 10 nm 20 nm 10 nm 0, 0001 0 5 10 15 20 Time - t - ns GMR resistance change - Write and Read For +1 V write and -1 V erase cycle NANOSMAT-Asia : Inter. Conf. Surf. , Coat. , Nano-Materials; Wuhan, CHINA, Mar. 13 -15, 2013 17

Spin. Valves - Charges 1 E+09 100 nm Number of Holons - QH 1 E+08 1 E+07 50 nm 1 E+06 1 E+05 20 nm 1 E+04 10 nm 1 E+03 1 E+02 Vo = + 1 V Vo = -1 V 1 E+01 0 5 10 15 20 Time - t - ns Holon charges - Write and Read For +1 V write and -1 V erase cycle NANOSMAT-Asia : Inter. Conf. Surf. , Coat. , Nano-Materials; Wuhan, CHINA, Mar. 13 -15, 2013 18

Spin. Valves - Conclusions The 10 nm film resistance change predicted by the QED induced photoelectric effect in GST films suggests superconductivity already exists or at least may be approached at ambient temperature. Superconductive nanowires are proposed* to sense single photons from an external source. C. Soci, et al. , “Nanowire Photodetectors, ” J. Nanoscience and Nanotechnology, 10, 1 -20, 2010 However, nanowires may be a natural QED induced superconductive interconnect in nanoelectronics. NANOSMAT-Asia : Inter. Conf. Surf. , Coat. , Nano-Materials; Wuhan, CHINA, Mar. 13 -15, 2013 19

Memristors 0, 8 Current - I - Amps 0, 6 0, 4 0, 2 0 -1, 5 -1 -0, 5 0 0, 5 1 1, 5 -0, 2 -0, 4 -0, 6 -0, 8 Voltage - Volts d = 50 nm , GST mobility H = 2 x 10 -6 cm 2/V-s QM creates Space Charge to change Memristor resistance ( HP claims Oxygen vacancies ) 20 NANOSMAT-Asia : Inter. Conf. Surf. , Coat. , Nano-Materials; Wuhan, CHINA, Mar. 13 -15, 2013

Ovshinsky Effect 10000000 Resistance - R - Ohms d = 1000 nm 1000000 100000 d = 100 nm 10000 d = 10 nm 1000 100 0, 1 1 10 1000 Time - t - ns Alq 3 Mobility = 2 x 10 -5 cm 2/V-s, Vo = 1 V, Ro = 1 M PCRAM resistance changes from QED Induced charge ( Melting is ambiguous) NANOSMAT-Asia : Inter. Conf. Surf. , Coat. , Nano-Materials; Wuhan, CHINA, Mar. 13 -15, 2013 21

1/f Noise in Nanowires Step in QED Induced Charge Step in Current Step in Power Fourier Transform of Step in Power gives 1/f Noise X(t) t - /2 QM creates holons as current enters nanowire ( Hooge relation based on free electrons ) NANOSMAT-Asia : Inter. Conf. Surf. , Coat. , Nano-Materials; Wuhan, CHINA, Mar. 13 -15, 2013 22

Conclusions By QM, submicron nanoelectronic circuit elements: Spin. Valves Memristors Ovshinsky Devices Nanowire Interconnects do not increase in temperature because Joule heat is conserved by the creation of charge. However, the QED induced charge may significantly increase the 1/f noise. 23 NANOSMAT-Asia : Inter. Conf. Surf. , Coat. , Nano-Materials; Wuhan, CHINA, Mar. 13 -15, 2013

Questions & Papers Email: nanoqed@gmail. com http: //www. nanoqed. org 24 NANOSMAT-Asia : Inter. Conf. Surf. , Coat. , Nano-Materials; Wuhan, CHINA, Mar. 13 -15, 2013