Croissance et proprits magntiques de rseaux planaires auto-organiss - PowerPoint PPT Presentation

Croissance et propriétés magnétiques de réseaux planaires auto-organisés de nanofils de Fer B. Borca, O.Fruchart, M. Hasegaw a, C. Meyer Laboratoire Louis Néel (CNRS-UJF-INPG) Grenoble Olivier Fruchart – JMC10 – Toulouse – Aug. 31st, 2006 http:/ / lab lab- - neel.grenoble.cnrs.fr neel.grenoble.cnrs.fr / / them es them es/ couches/ / couches/ ext ext / / slides slides/ / http:/ / http:/ / lab-neel.grenoble.cnrs.fr/ them es/ couches/ ext/ slides/

INTRODUCTION – Context Self-organization at surfaces : 2D regular arrays of similar nanostructures Stripes and wires Dots Co/Au(111) Co/Pt(997) 350 x 350 nm A. Dallm eyer et al., PRB 6 1 ( 8 ) , R5 1 5 3 ( 2 0 0 0 ) D.D. Cham bliss et al., PRL 6 6 , 1 7 2 1 ( 1 9 9 1 ) B.Voigtlander et al., PRB 4 4 , 1 0 3 5 4 ( 1 9 9 1 ) P. Gam bardella et al., Nature 4 1 6 , 3 0 1 ( 2 0 0 2 ) J. P. Bucher et coll.; S. Rousset et coll.; P. Gam bardella et al., Science 3 0 0 , 1 1 3 0 ( 2 0 0 3 ) O. Fruchart et coll. What for? � Cheaper and beyond lithography � Fundamental research: weak distributions > reliable analysis � Applications? lack of versatility (tunability; use no vicinal nor reconstructed surface) Olivier Fruchart – JMC10 – Toulouse – Aug. 31st, 2006 – p.2 Laboratoire Louis N Laboratoire Louis Né éel, Grenoble el, Grenoble, France , France. . Laboratoire Louis Néel, Grenoble, France. http:/ / lab http:/ / lab- - neel.grenoble.cnrs.fr neel.grenoble.cnrs.fr / / them es them es/ couches/ / couches/ ext ext / / slides slides/ / http:/ / lab-neel.grenoble.cnrs.fr/ them es/ couches/ ext/ slides/

INTRODUCTION – Self-organization without reconstructions or steps Demonstrated path: ion etching Stripes and wires Dots Ag GaSb(001) 200nm T. Aste and U. Valbusa, New J. Phys. 7 , 1 2 2 ( 2 0 0 5 ) F. Facsko et al., Science 2 8 5 , 1 5 5 1 ( 1 9 9 9 ) Magnetic wires � Etched magnetic films (with or without mask) Olivier Fruchart – JMC10 – Toulouse – Aug. 31st, 2006 – p.3 Laboratoire Louis N Laboratoire Louis Né éel, Grenoble el, Grenoble, France , France. . Laboratoire Louis Néel, Grenoble, France. http:/ / lab http:/ / lab- - neel.grenoble.cnrs.fr neel.grenoble.cnrs.fr / / them es them es/ couches/ / couches/ ext ext / / slides slides/ / http:/ / lab-neel.grenoble.cnrs.fr/ them es/ couches/ ext/ slides/

INTRODUCTION – Self-organization without reconstructions or steps Hills and grooves by kinetically-limited growth on bcc(110) W(110) homoepitaxy Fe(110) homoepitaxy LEED STM Simulation U. Köhler et al., Surf. Sci. 4 5 4 -4 5 6 , 6 7 6 ( 2 0 0 0 ) M. Albrecht et al., Surf. Sci. 2 9 4 , 1 ( 1 9 9 3 ) � Any use for magnetic wires? Olivier Fruchart – JMC10 – Toulouse – Aug. 31st, 2006 – p.4 Laboratoire Louis N Laboratoire Louis Né éel, Grenoble el, Grenoble, France , France. . Laboratoire Louis Néel, Grenoble, France. http:/ / lab http:/ / lab- - neel.grenoble.cnrs.fr neel.grenoble.cnrs.fr / / them es them es/ couches/ / couches/ ext ext / / slides slides/ / http:/ / lab-neel.grenoble.cnrs.fr/ them es/ couches/ ext/ slides/

GROWTH – UHV-PLD chambers Pulsed Laser Deposition (DLP) in UHV Nd:YAG pulsed laser cc(110)/Al 2 O 3 (11-20) cc=Mo, W, Nb, etc. Target Analysis Wedges • RHEED (Reflection High-Energy Electron Diffraction) • STM (Scanning Tunneling Microscopy) Mask • AES (Auger Electron Spectroscopy) Substrate Olivier Fruchart – JMC10 – Toulouse – Aug. 31st, 2006 – p.5 Laboratoire Louis N Laboratoire Louis Né éel, Grenoble el, Grenoble, France , France. . Laboratoire Louis Néel, Grenoble, France. http:/ / lab http:/ / lab- - neel.grenoble.cnrs.fr neel.grenoble.cnrs.fr / / them es them es/ couches/ / couches/ ext ext / / slides slides/ / http:/ / lab-neel.grenoble.cnrs.fr/ them es/ couches/ ext/ slides/

GROWTH – Trenches: Mo (1/2) Buffer layers for trenches Mo Deposition of bcc refractory metals along (110) RT deposition Annealed 800°C RT-150°C deposition [1-10] [001] 50nm 200nm 50nm Mo Mo Mo Mo Al 2 O 3 Al 2 O 3 Al 2 O 3 � Uniaxial array of trenches (epitaxial) � Long-range orientational order Olivier Fruchart – JMC10 – Toulouse – Aug. 31st, 2006 – p.6 Laboratoire Louis N Laboratoire Louis Né éel, Grenoble el, Grenoble, France , France. . Laboratoire Louis Néel, Grenoble, France. http:/ / http:/ / lab lab- - neel.grenoble.cnrs.fr neel.grenoble.cnrs.fr / / them es them es/ couches/ / couches/ ext ext / / slides slides/ / http:/ / lab-neel.grenoble.cnrs.fr/ them es/ couches/ ext/ slides/

GROWTH – Trenches: Mo (2/2) RHEED STM Mo, RT, annealed Mo, RT [1-10] 200nm 50nm [001] [-110] 8nm (110) [001] [001] (110) [1-10] Olivier Fruchart – JMC10 – Toulouse – Aug. 31st, 2006 – p.7 Laboratoire Louis N Laboratoire Louis Né éel, Grenoble el, Grenoble, France , France. . Laboratoire Louis Néel, Grenoble, France. http:/ / lab http:/ / lab- - neel.grenoble.cnrs.fr neel.grenoble.cnrs.fr / / them es them es/ couches/ / couches/ ext ext / / slides slides/ / http:/ / lab-neel.grenoble.cnrs.fr/ them es/ couches/ ext/ slides/

GROWTH – Trenches: atomic structure Atomic structure of the facets Facets of type {210} θ =18.43° (110) [1-10] [001] (00-1) [1-10] Figures for Mo (110) � Lateral period ~5 nm � Depth of trenches: 0.6-1 nm Olivier Fruchart – JMC10 – Toulouse – Aug. 31st, 2006 – p.8 Laboratoire Louis N Laboratoire Louis Né éel, Grenoble el, Grenoble, France , France. . Laboratoire Louis Néel, Grenoble, France. http:/ / lab http:/ / lab- - neel.grenoble.cnrs.fr neel.grenoble.cnrs.fr / / them es them es/ couches/ / couches/ ext ext / / slides slides/ / http:/ / lab-neel.grenoble.cnrs.fr/ them es/ couches/ ext/ slides/

GROWTH – Trenches: W (1/2) Process for W STM RHEED W deposited at 150°C W W [-110] Mo Al 2 O 3 (110) [001] 20nm Lateral period ~5.5 nm Satellite streaks � Order is improved with W > Lateral period ~5.5 nm Olivier Fruchart – JMC10 – Toulouse – Aug. 31st, 2006 – p.9 Laboratoire Louis N Laboratoire Louis Né éel, Grenoble el, Grenoble, France , France. . Laboratoire Louis Néel, Grenoble, France. 9 9 9 http:/ / lab http:/ / lab- - neel.grenoble.cnrs.fr neel.grenoble.cnrs.fr / / them es them es/ couches/ / couches/ ext ext / / slides slides/ / http:/ / lab-neel.grenoble.cnrs.fr/ them es/ couches/ ext/ slides/

GROWTH – Trenches: W (2/2) W deposited under decreasing temperature: 550°C � 150°C RHEED STM >>> RHEED video 20 Angle of facets (°) 15 10 20nm 5 0 0 5 10 15 20 25 30 Thickness (Å) � Well-defined facets � {210} is the limiting facet � Period ~ 10-12 nm [contrary to statement of Köhler et al. � Depth ~ 2-3 nm On small trenches, {310} (2000)] Olivier Fruchart – JMC10 – Toulouse – Aug. 31st, 2006 – p.10 Laboratoire Louis N Laboratoire Louis Né éel, Grenoble el, Grenoble, France , France. . Laboratoire Louis Néel, Grenoble, France. http:/ / lab http:/ / lab- - neel.grenoble.cnrs.fr neel.grenoble.cnrs.fr / / them es them es/ couches/ / couches/ ext ext / / slides slides/ / http:/ / lab-neel.grenoble.cnrs.fr/ them es/ couches/ ext/ slides/

GROWTH – Fe (1/2) Fe/W(110) with small period (5nm) at 150°C 5 1.7ML Fe Fe - 1.5 ML 1.5ML Fe 4 Cross-section (nm) 1.2ML Fe 3 1ML Fe 2 0.8ML Fe 150nm x 150nm 0.5ML Fe 1 W Fe – 1 ML 0 0 5 10 15 20 25 30 Fe - 2.4 ML Distance (across wires) � Layer-by-layer growth � Forms a smooth surface Fe - 1.8 ML [001] Olivier Fruchart – JMC10 – Toulouse – Aug. 31st, 2006 – p.11 Laboratoire Louis N Laboratoire Louis Né éel, Grenoble el, Grenoble, France , France. . Laboratoire Louis Néel, Grenoble, France. http:/ / http:/ / lab lab- - neel.grenoble.cnrs.fr neel.grenoble.cnrs.fr / / them es them es/ couches/ / couches/ ext ext / / slides slides/ / http:/ / lab-neel.grenoble.cnrs.fr/ them es/ couches/ ext/ slides/

GROWTH – Fe (2/2) Some details about continuous films Residual corrugation across the trenches Zoology of misfit dislocations Olivier Fruchart – JMC10 – Toulouse – Aug. 31st, 2006 – p.12 Laboratoire Louis N Laboratoire Louis Né éel, Grenoble el, Grenoble, France , France. . Laboratoire Louis Néel, Grenoble, France. http:/ / http:/ / lab lab- - neel.grenoble.cnrs.fr neel.grenoble.cnrs.fr / / them es them es/ couches/ / couches/ ext ext / / slides slides/ / http:/ / lab-neel.grenoble.cnrs.fr/ them es/ couches/ ext/ slides/

Magnetism – Mo/Fe/W Structure Magnetism 2.5ML Fe/W(110) with large period (12nm) at 150°C Mo Capping for Fe SQUID W measurements 1.0 H//[001] 0.5 M/M S 4K 0.0 25K -0.5 50K 100K -1.0 -400 -200 0 200 400 B (mT) 4 -9 ) Applied field 10 mT 2 x 10 3 FC Moment (A.m 2 1 ZFC 0 0 50 100 150 200 250 300 Temperature (K) � Easy axis along in-plane [001] � Fe stripes at the bottom of the trenches � Mean blocking temperature 100K Olivier Fruchart – JMC10 – Toulouse – Aug. 31st, 2006 – p.13 Laboratoire Louis N Laboratoire Louis Né éel, Grenoble el, Grenoble, France , France. . Laboratoire Louis Néel, Grenoble, France. http:/ / lab http:/ / lab- - neel.grenoble.cnrs.fr neel.grenoble.cnrs.fr / / them es them es/ couches/ / couches/ ext ext / / slides slides/ / http:/ / lab-neel.grenoble.cnrs.fr/ them es/ couches/ ext/ slides/