MAGNETIC STUDY OF MANGANITE SUPERLATTICES PREPARED BY MOCVD

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MAGNETIC STUDY OF MANGANITE SUPERLATTICES
PREPARED BY MOCVD
Carla Abilio
C. Abílio and M. Godinho Dept de Física/CCMM,
Faculdade de Ciências Univ. Lisboa, Portugal M.
Rosina, C. Dubourdieu and F. Weiss Laboratoire
des Matériaux et du Génie Physique, ENSPG,
France M. Rosina and K. Frohlich Institute of
Electrical Engineering, SAS, Bratislava,
Slovekia
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(La0.7Sr0.3MnO3/SrTiO3)15 Superlattices

• Pulsed laser deposition MOCVD
• 15 intercalated layers of thickness
• La0.7Sr0.3MnO3 1.9 nm to 12.4 nm
• SrTiO3 3.1 nm
• (001) SrTiO3 substrate
• 0.8 lattice mismatch with LSMO gt
• In-plane tensile
  strain

15 x La0.7Sr0.3MnO3/SrTiO3
LMGP - ENSPG, France
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OUTLINE

• Evolution with LSMO thickness of
• ferromagnetic transition
• coercive field
• volume saturation magnetization
• Dependence of magnetization on direction between
  field
• 
  and sample plane

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SPONTANEOUS MAGNETIZATIONafter Field Cooling _at_
Hll 50 Oe
LSMO thin films
LSMO/STO Multilayers
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Evolution of Tc,onset and Tirrev with thickness
Bulk values Tcurie 369 K 100 nm film
Tc,onset 360 K
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Hysteresis loops _at_ Hll and T 5 K
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Thickness dependence of in-plane Hcoercive
100 nm film Hcoercive 60 Oe (5K) Hcoercive 35
Oe (35K)
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Thickness dependence of Msaturation
100 nm film Msat 665 emu/cm3
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Longitudinal and Transverse Magnetizationwith
varying field direction
H
q
Hin-plane H cos q
Mlong
Mtransv

• Sample is field cooled 380 -gt 35 K _at_ H//
  1 T
• Mlong and Mtransv are measured simultaneously
  as a function of q

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Longitudinal Magnetization _at_ H lt Hcoercive
q
q
Mlong
T 35 K
Multilayer (LSMO 12. 4nm)
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Longitudinal and Transverse Magnetization _at_ H lt
Hcoercive
Mtransv
Multilayer (LSMO 12. 4nm)
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Longitudinal and Transverse Magnetization _at_
H gt H//,coercive
T 35 K
Multilayer (LSMO 12. 4nm)
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LSMO thickness 3.1 nm H 200 Oe
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Summary

• Correlation between thickness and magnetic
  properties
• Tc and Msat decreases with decreasing thickness
• Hcoercive (at low T) increases with decreasing
  thickness

• in-plane easy-axis for magnetization
• H lt H //,coercive, M rotates with sample
• small H gt H //,coercive
• in-plane H gt H //,coercive, M rotates in
  sample plane towards
• the field direction
• in-plane H lt H //,coercive, misalignment of
  magnetic domains