III Electronic Transport & Organic Spin Electronics S i El t i P. Stamenov Introduction to transport devices – ‘…from junctions to transistors.’ Organic electronics – g ‘…from small molecules to polymers.’ Andreev Reflection – ‘So, what is the spin polarization?...’ ‘So what is the spin polarization? ’ Fermiology – ‘Either I mistake your shape and making quite; Or else you are that shrewd and knavish sprite…’ Planned work- ‘ …for the remainder of the programme. for the remainder of the programme ’ NISE Tasks 3, 4 – Organics, Organic Spin Transistor NISE Tasks 2, 8 – Interface Layers, New Materials NISE Review 7-ix-2012
Staff, Publications • Plamen Stamenov Lecturer • Franklyn Burke Postgrad (Graduated early 2011) • Huseyin Tokuc Postgrad Huseyin Tokuc Postgrad • Simone Alborghetti Postgrad (from September 2011) MAGNETISM & SPIN ELECTRONICS NISE Midterm Review Trinity College Dublin
Publications: (This strand only) — Stamenov, P. " Point Contact Andreev Reflection from Erbium: Andreev Reflection from Erbium: The Role of External Magnetic Field and the Sign of the Spin Polarization " from Erbium: The Role of External Magnetic Field and the Sign of the Spin Polarization Journal of Applied Physics 111 , 7 (2012) — Alborghetti, S., Coey, J.M.D. & Stamenov, P., Dependence of charge carrier injection " Dependence of charge carrier injection Alborghetti S Coey J M D & Stamenov P on the interface energy barrier in short-channel polymeric field effect transistors ", Applied Physics Letters, 100 , 14 (2012) — Burke, F., Stamenov, P. & Coey, J.M.D., " Charge injection, transport and localization in rubrene ", Synthetic Metals, 161 , 7-8, pp. 563-569 (2011) — Kurt, H., Rode, K., Venkatesan, M., Stamenov, P. & Coey, J.M.D., " High spin polarization in epitaxial films of ferrimagnetic Mn 3 Ga ", Physical Review B - Condensed Matter and Materials Physics, 83 , 2 (2011) — Kurt, H., Rode, K., Venkatesan, M., Stamenov, P. & Coey, J.M.D., " Mn 3-x Ga (0 ≤ x ≤ 1): Multifunctional thin film materials for spintronics and magnetic recording ", Physica Status Solidi (B) Basic Research, 248 , 10, pp. 2338-2344 (2011) — Monzon, L.M.A., Burke, F. & Coey, J.M.D., " Optical, magnetic, electrochemical, and electrical properties of 8-hydroxyquinoline-based complexes with Al 3+ , Cr 3+ , Mn 2+ , Co 2+ , Ni 2+ , Cu 2+ , and Zn 2+ ", Journal of Physical Chemistry C, 115 , 18, pp. 9182-9192 (2011) MAGNETISM & SPIN ELECTRONICS NISE Midterm Review Trinity College Dublin
Publications: (continued…) — Stamenov, P. & Coey, J.M.D., " Fermi level spin polarization of polycrystalline thulium by point contact Andreev reflection spectroscopy ", Journal of Applied Physics 109 7 (2011) Physics, 109 , 7 (2011) — Tokuc, H., Oguz, K., Burke, F. & Coey, J.M.D., " Magnetoresistance in CuPc based organic magnetic tunnel junctions " Journal of Physics: Conference Series based organic magnetic tunnel junctions , Journal of Physics: Conference Series, 303 , 1 (2011) — Venkatesan, M., Tokuc, H., Burke, F., Szulczewski, G. & Coey, J.M.D., Venkatesan, M., Tokuc, H., Burke, F., Szulczewski, G. & Coey, J.M.D., " Magnetic properties of the Co/Alq 3 interface ", Journal of Applied Physics, 109 , 7 (2011) MAGNETISM & SPIN ELECTRONICS NISE Midterm Review Trinity College Dublin
Introduction Junctions & Devices Metallic Structures Metal-Organic GMR and TMR (Non GMR) Contacts Junctions Anomalous Magnetoresistance Large Area Junctions Structures (In-plane Electronic & Magnetic Field Effects Anisotropy) Magnetic Response & Spin Injection/Detection Spontaneous Hall Effect Structures & Sensors (Linear Response) Perpendicular Anisotropy & Low Barrier Height Junctions Field & Current Driven for Spin Injection Switching Switching Point Contacts & Andreev Oscillatory & Short Channel Transistors Reflection Reflection High Frequency Response High Frequency Response MAGNETISM & SPIN ELECTRONICS NISE Midterm Review Trinity College Dublin
Introduction Ferromagnetic Ferromagnetic Ferromagnetic Ferromagnetic Light ? Light ? Spin P Metal ( Fe ) ? Metal ( Fe ) ? Spin or or or Heat ? Ferromagnetic Ferromagnetic Ferromagnetic Ferromagnetic or or Probe Pump Semiconductor Semiconductor Magnetic Mn:GaAs , Mn:GaAs, Field ? ( Co:ZnO ) ? ( ) ( Co:ZnO ) ? ( ) Spin Injector Spin Transmitting Spin Detector Media Spin Manipulator Normal M-M Junction ? Electrostatic Metal ( Al ) ? or Gate ? or Schottky Junction ? or Semiconductor ( Si ) ( ) or External Magnetic or Tunnel Junction ? MAGNETISM & Field ? Semimetal ( C ) ? SPIN ELECTRONICS Trinity College Dublin
Organics - Tools • Two different deposition tools have been employed for the production of organic and metal/organic stacks • The ‘Shamrock’ sputtering/UHV e-beam evaporation system • The ‘Magnolia’ UHV thermal evaporator with integrated low angle argon milling MAGNETISM & SPIN ELECTRONICS NISE Midterm Review Trinity College Dublin
Organics - Rubrene MAGNETISM & SPIN ELECTRONICS Trinity College Dublin
Organics - Rubrene MAGNETISM & SPIN ELECTRONICS NISE Midterm Review Trinity College Dublin
Organics Rubrene B2B Schottky -10 -7 -6 7.5x10 1.5x10 T = 300 K 2 K 2 I ** = 150 A/cm 20 20 m -3 3 -10 -7 N d = 1.10 5.0x10 1.0x10 300 K V bi = 10 mV 7 R s = 0.1*10 Exp. Data -10 -8 -8 1 = 0.215 eV 2.5x10 5.0x10 Fits 2 = 0.213 eV T = 200 K ent (A) 1 = 8.466 nm I /1 A) 2 K 2 I ** = 60 A/cm 0.0 2 = 5.872 nm 0.0 -3 N d = 1e20 m Curre 1 = 1.903 log( I 1 903 V bi = 10 mV 2 = 2.596 7 R s = 2*10 200 K -10 -8 -10 -2.5x10 1 = 0.223 eV -5.0x10 2 = 0.233 eV 1 = 9.289 nm -10 -7 -5.0x10 2 = 8.603 nm -1.0x10 1 = 5.532 2 = 0.987 -10 -7 -12 -7.5x10 -1.5x10 -2 -1 0 1 2 -2 -1 0 1 2 Applied Bias (V) Applied Bias (V) -7 1.5x10 Rubrene NiFe A79 273 nm Dec -7 7 creasing T 1.0x10 1 0 10 -8 5.0x10 0.0 (A) I ( -8 -5.0x10 -7 -1.0x10 -7 -1.5x10 -2 -1 0 1 2 MAGNETISM & U (V) SPIN ELECTRONICS NISE Midterm Review Trinity College Dublin
Rubrene - WLMR -12 2.0x10 Data Fit -12 1.5x10 Residue Rubrene/NiFe A80 T = 10 K T 10 K ctance (S) -12 1.0x10 L 0 = 0.6 a 0 L 1 = 136 nm L 2 = 66 nm -13 5.0x10 5 0x10 2 ed Conduc 0.0 Detrende -13 -5.0x10 -12 12 -1.0x10 -12 -1.5x10 -15 15 -10 10 -5 5 0 0 5 5 10 10 15 15 Magnetic Field (T) • 2D Weak Delocalisation model has been used to fit the data ( T = 3 K) and extract three different localisation scales – the longest one (136 nm) likely t t th diff t l li ti l th l t (136 ) lik l due to spin scattering MAGNETISM & SPIN ELECTRONICS • The effect vanishes very quickly and is unobservable above about 20 K NISE Midterm Review Trinity College Dublin
Organics - Rubrene MAGNETISM & SPIN ELECTRONICS NISE Midterm Review Trinity College Dublin
Organics – P3HT MAGNETISM & SPIN ELECTRONICS NISE Midterm Review Trinity College Dublin
Organics – P3HT a) b) Organic film SAM Drain Source NiFe NiFe SiO 2 A n ++ silicon Gate MAGNETISM & SPIN ELECTRONICS NISE Midterm Review Trinity College Dublin
Organics – P3HT & Alq3 MAGNETISM & SPIN ELECTRONICS NISE Midterm Review Trinity College Dublin
Organics – Alq 3 & Pentacene MAGNETISM & SPIN ELECTRONICS NISE Midterm Review Trinity College Dublin
PCAR Basics MAGNETISM & SPIN ELECTRONICS • Taken from: Soulen R. J. et. al. Science 282 85 (1998) Trinity College Dublin
PCAR Hardware • 1.8 K < T <400 K, 0 < B < 1 T • Micromechanical & Piezo motion • Thin films and Single crystals MAGNETISM & • Fast – > 1 spectrum per second SPIN ELECTRONICS Trinity College Dublin
Setup and Some Important Considerations 1 Considerations 1 Micro- mechanical pushrod Superconductin g tip Contact terminals Sample support Piezo drive High MAGNETISM & Voltage SPIN ELECTRONICS insulation Trinity College Dublin
Setup and Some Important Considerations 2 Considerations 2 Sample layer(s) layer(s) Substrate chip MAGNETISM & SPIN ELECTRONICS Trinity College Dublin
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