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Correlation between structure and magnetism in thin films INFM, Unità di Genova Francesco Bisio.

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Presentation on theme: "Correlation between structure and magnetism in thin films INFM, Unità di Genova Francesco Bisio."— Presentation transcript:

1 Correlation between structure and magnetism in thin films INFM, Unità di Genova Francesco Bisio

2 Experimental techniques: Magnetism+ structure in situ MOKE + MSHG, Polar+longitudinal QLEED UHV chamber:p~1.5·10 -10 mbar; Electromagnet ~800 Oe; MOKE: 670 nm laser diode; SHG: Ti:sapphire 720÷880 nm, <100fs pulse. viewport sample Phosphor- screen Magnet LEED Laser 670 nm viewport polarizer Monochr. PMT

3 sample Magnet Magnetism + Structure: Fe/Cu 3 Au T=185 K SRO Onset of Magnetic order POLAR Magnet sample Magnet LONGITUDINAL SRO T=290 K sample Magnet LEED (00) (11)

4 Fe/Cu 3 Au thin films Fcc substrate, a=3.745 Å Possibility of stabilising metastable Fe structures Possible coexistence of different structural phases within the same film AF NM FM P. M. Marcus et al. PRB 60, 369 (1999) R ws (a. u.) Fcc Fe: Magnetic properties depend upon lattice parameter (110) (100) (-110) a=2.65 Å c/a= 2 Au Cu Fe

5 Fe / Cu 3 Au: structural properties Intensity [a. u.] Bcc Fe R45° H [r. l. u.] Substrate, Pseudomorphic Fe F. Bruno et al. PRB 66, 045402 GIXRD radial scans vs. film thickness

6 Structure and morphology ~150 Å thk >30 Å Low coverage: thk<10 Å Medium coverage: 10 Å25 Å Fe substrate Fe substrate Fe substrate Fe

7 Structure-magnetism correlation Cu 3 Au Cu 3 Au Cu 3 Au T dep ~295 K Hext=± 50 Oe Hext|| (100) M M M Optical – Magneto Optical response ? Interface hybridization ? Different per atom ?

8 Morphology-magnetism correlation T dep ~295 K Hext=± 50 Oe H ext || (100) T dep ~295 K Hext=± 50 Oe H ext || (110)

9 Morphology-magnetism correlation H ext || (100) H ext || (110)

10 Temperature dependence of magnetic properties Morphological effect Intermixing + Curie temperature shift Kerr asymmetry during growth vs. substrate temperature

11 People Università di Genova e UdR INFM G. Gonella R. Moroni S. Terreni M. Canepa L. Mattera

12 Conclusions Experimental apparatus devoted to the study of structure-magnetism correlation; Application to heteroepitaxial ultrathin magnetic films; Study of buried interface properties (MSHG); Dependence of magnetism upon crystallographic parameters;

13 sample Magnet LEED Experimental techniques: real time MOKE T=185 K SRO Onset of Magnetic order POLAR Fe/Cu 3 Au sample Magnet LEED LONGITUDINAL SRO T=290 K Fe/Cu 3 Au

14 Intensity [a. u.] H [r. l. u.] Fe/Cu 3 Au: structural properties Coexistence of multiple structural phases on the film In-depth scan of the film


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