HAL Id: tel-00864726
https://tel.archives-ouvertes.fr/tel-00864726
Submitted on 23 Sep 2013
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Impact of structural defects on spin-polarized transport
across magnetic tunnel junctions
Filip Schleicher
To cite this version:
P❛rt ■
❚❤❡♦r❡t✐❝❛❧ ❇❛s✐s
P❛rt ■■
❊①♣❡r✐♠❡♥t❛❧ r❡❛❧✐③❛t✐♦♥
✸✳✷✳ ❙❯❇❙❚❘❆❚❊ P❘❊P❆❘❆❚■❖◆ ✽✼
❋✐❣✉r❡ ✸✳✶✿ ❆t♦♠✐❝ ❋♦r❝❡ ▼✐❝r♦s❝♦♣② t♦♣♦❣r❛♣❤✐❝❛❧ ♠❛♣s ♦❢ t❤❡ r❛✇ ✭t♦♣✮✱ ❛♥♥❡❛❧❡❞ ✭❝❡♥t❡r✮ ❛♥❞ ❡t❝❤❡❞ t❤❡♥ ❛♥♥❡❛❧❡❞ ✭❜♦tt♦♠✮ ▼❣❖ s✉❜str❛t❡✳ ❆t♦♠✐❝ st❡♣s ❛r❡ ✈✐s✐❜❧❡ ♦♥ t❤❡ ❧❛tt❡r t✇♦✳
✺✳✸✳ ❖P❚■❈❆▲ ❙❚❯❉■❊❙ ✶✶✼ ❋✐❣✉r❡ ✺✳✶ s❝❤❡♠❛t✐❝❛❧❧② s❤♦✇s t❤❡ ❜❡❤❛✈✐♦r ♦❢ ❛ ♣♦t❡♥t✐❛❧ ❜❛rr✐❡r ✇✐t❤ ❡q✉❛❧ ❤❡✐❣❤ts ❛t ❡❛❝❤ ✐♥t❡r❢❛❝❡ t❤❛t ✐s ✈♦❧t❛❣❡✲❜✐❛s❡❞ ✇✐t❤ t✇♦ ❞✐✛❡r❡♥t ❡①t❡r♥❛❧ ✈♦❧t❛❣❡ r❛♥❣❡ ❝❛s❡s✳ ■❢ t❤❡ ❛♣♣❧✐❡❞ ✈♦❧t❛❣❡ V +dV ✐s ❧♦✇❡r t❤❛♥ t❤❡ ❜❛rr✐❡r ❤❡✐❣❤t✱ t❤❡ ❜❛rr✐❡r ❛✈❡r❛❣❡ ❤❡✐❣❤t ❞❡❝r❡❛s❡s ❛❧♦♥❣ ✇✐t❤ t❤❡ dV ✈♦❧t❛❣❡ ✐♥❝r❡❛s❡ ❜✉t ✐ts ✇✐❞t❤ r❡♠❛✐♥s ❝♦♥st❛♥t✳ ❍♦✇❡✈❡r✱ ✐❢ t❤❡ V + dV ❡①❝❡❡❞s t❤❡ ❜❛rr✐❡r ❤❡✐❣❤t✱ t❤❡ dV ❜✐❛s ✈♦❧t❛❣❡ ✐♥❝r❡♠❡♥t ❝❛✉s❡s ♥♦t ♦♥❧② ❛ ❞❡❝r❡❛s❡ ♦❢ t❤❡ t❤❡ ❛✈❡r❛❣❡ ❜❛rr✐❡r ❤❡✐❣❤t✱ ❜✉t ♦❢ ✐ts ✇✐❞t❤ ❛s ✇❡❧❧✱ ❧❡❛❞✐♥❣ t♦ ❛♥ ❛❞❞✐t✐♦♥❛❧✱ ♠♦r❡ ♣r♦♠✐♥❡♥t r✐s❡ ✐♥ ❥✉♥❝t✐♦♥ ❝♦♥❞✉❝t❛♥❝❡✳
✺✳✷✳✸ ˆI ♠❡t❤♦❞
❚❤❡ s❡❝♦♥❞ ♠❡t❤♦❞ ♣r♦♣♦s❡❞ ❜② ❘♦tt❧❛♥❞❡r ❡t ❛❧ ✇❛s ❡①t❡♥s✐✈❡❧② ✉s❡❞ ✇✐t❤✐♥ t❤❡ t✐♠❡❢r❛♠❡ ♦❢ t❤✐s t❤❡s✐s✳ ■t r❡q✉✐r❡s ♣❡r❢♦r♠✐♥❣ ❝✉rr❡♥t✲✈♦❧t❛❣❡ ❝❤❛r❛❝t❡r✐st✐❝s ❛t t✇♦ ❞✐✛❡r❡♥t t❡♠♣❡r❛t✉r❡s✳ ❆s t❤❡ ❋❡r♠✐ ❧❡✈❡❧ st❛rts t♦ s♠❡❛r ♦✉t ✇✐t❤ t❤❡ ✐♥✲ ❝r❡❛s✐♥❣ t❡♠♣❡r❛t✉r❡✱ t❤❡ ❝✉rr❡♥t t✉♥♥❡❧s ♠♦st ❡✣❝✐❡♥t❧② ❢♦r ✈♦❧t❛❣❡s ❥✉st ❛❜♦✈❡ t❤❡ ❜❛rr✐❡r ❤❡✐❣❤t ♦❢ t❤❡ ♣♦s✐t✐✈❡❧② ❜✐❛s❡❞ ❡❧❡❝tr♦❞❡✳ ❚❤❡ ♥♦r♠❛❧✐③❡❞ t❡♠♣❡r❛t✉r❡ ❞❡♣❡♥❞❡♥❝❡ ②✐❡❧❞s ✐♥❝r❡❛s❡❞ ✈❛❧✉❡s ❛r♦✉♥❞ t❤❡ ❜❛rr✐❡r ❤❡✐❣❤t ❧❡✈❡❧ ♦❢ t❤❡ ♣♦s✐t✐✈❡❧② ❜✐❛s❡❞ ❡❧❡❝tr♦❞❡✿ ˆI(V ) = I(V, T2) − I(V, T1) I(V, T1)
❙✉❝❤ ♠❡❛s✉r❡♠❡♥ts✱ ♦♥❝❡ ♣❡r❢♦r♠❡❞ ♦♥ ❛ ✇✐❞❡ r❛♥❣❡ ♦❢ t❡♠♣❡r❛t✉r❡s ✭ˆIT1−T2✱
ˆ
IT2−T3✱ ˆIT3−T4 ❛♥❞ s♦ ♦♥✮✱ ❝❛♥ ②✐❡❧❞ ✐♥s✐❣❤t ✐♥t♦ t❤❡ ❛❝t✐✈❛t✐♦♥ t❡♠♣❡r❛t✉r❡ ❛♥❞
✈♦❧t❛❣❡ ♦❢ ❝❡rt❛✐♥ ♠❛❣♥❡t♦tr❛♥s♣♦rt ❢❡❛t✉r❡s✳ ❚❤❡② ❛r❡ ❝❛❧❧❡❞ r❡❧❛t✐✈❡ ˆI ♦r ˆIrel ❛s
♦♣♣♦s❡❞ t♦ ❛❜s♦❧✉t❡ ˆI ♦r ˆIabs s❡r✐❡s✱ ✐♥ ✇❤✐❝❤ ❛❧❧ t❤❡ ❞❛t❛ ✐s ♣❧♦tt❡❞ ✐♥ r❡❢❡r❡♥❝❡ t♦
P❛rt ■■■
❉❡✈✐❝❡ st✉❞②
✻✳✸✳ ❈❖◆❈▲❯❙■❖◆❙ ❆◆❉ ▼❖❱❊ ❚❖❲❆❘❉❙ ▲❙▼❖ ✶✸✼ ♣❡r❢♦r♠❛♥❝❡ r❡s✉❧ts ❢r♦♠ t❤❡ s❡❝♦♥❞ ❝❛s❡✱ ❛ ♠♦r❡ st❛❜❧❡ ❙✐❖2 ♦r ❡✈❡♥ t❤❡ s✐❧✐❝♦♥
✼✳✸✳ ❈♦❋❡❇✴▼❣❖✴❈♦❋❡❇ ✶✺✾
❋✐❣✉r❡ ✼✳✶✾✿ ˆIrel ❝✉r✈❡s ❢♦r t❤❡ ❛♥♥❡❛❧❡❞ ❞❡✈✐❝❡ ✐♥ t❤❡ P ✭t♦♣✮ ❛♥❞ ❆P ✭❜♦tt♦♠✮
✼✳✸✳ ❈♦❋❡❇✴▼❣❖✴❈♦❋❡❇ ✶✻✺
❋✐❣✉r❡ ✼✳✷✷✿ ˆIrel ❝✉r✈❡s ❢♦r ❛ ♥♦♥✲❛♥♥❡❛❧❡❞ ❞❡✈✐❝❡ ✐♥ t❤❡ P ✭t♦♣✮ ❛♥❞ ❆P ✭❜♦tt♦♠✮
P❛rt ■❱
❈♦♥❝❧✉s✐♦♥s ❛♥❞ ♣❡rs♣❡❝t✐✈❡s
❇■❇▲■❖●❘❆P❍❨ ✶✽✸ ❬✹✷❪ ❏✳✲▲✳ ▼❛✉r✐❝❡✱ ❉✳ ■♠❤♦✛✱ ❏✳✲P✳ ❈♦♥t♦✉r✱ ❛♥❞ ❈✳ ❈♦❧❧✐❡①✱ ✏■♥t❡r❢❛❝❡s ✐♥ ✶✵✵ ❡♣✐✲ t❛①✐❛❧ ❤❡t❡r♦str✉❝t✉r❡s ♦❢ ♣❡r♦✈s❦✐t❡ ♦①✐❞❡s✱✑ P❤✐❧♦s♦♣❤✐❝❛❧ ▼❛❣❛③✐♥❡✱ ✈♦❧✳ ✽✻✱ ♥♦✳ ✶✺✱ ♣♣✳ ✷✶✷✼✕✷✶✹✻✱ ✷✵✵✻✳ ❬✹✸❪ ▼✳ ❇♦✇❡♥✱ ❆✳ ❇❛rt❤é❧é♠②✱ ❱✳ ❇❡❧❧✐♥✐✱ ▼✳ ❇✐❜❡s✱ P✳ ❙❡♥❡♦r✱ ❊✳ ❏❛❝q✉❡t✱ ❏✳✲P✳ ❈♦♥t♦✉r✱ ❛♥❞ P✳ ❍✳ ❉❡❞❡r✐❝❤s✱ ✏❖❜s❡r✈❛t✐♦♥ ♦❢ ❢♦✇❧❡r✕♥♦r❞❤❡✐♠ ❤♦❧❡ t✉♥♥❡❧✐♥❣ ❛❝r♦ss ❛♥ ❡❧❡❝tr♦♥ t✉♥♥❡❧ ❥✉♥❝t✐♦♥ ❞✉❡ t♦ t♦t❛❧ s②♠♠❡tr② ✜❧t❡r✐♥❣✱✑ P❤②s✳ ❘❡✈✳ ❇✱ ✈♦❧✳ ✼✸✱ ♣✳ ✶✹✵✹✵✽✱ ❆♣r ✷✵✵✻✳ ❬✹✹❪ ■✳ ❏✳ ❱❡r❛ ▼❛rú♥✱ ❋✳ ▼✳ P♦st♠❛✱ ❏✳ ❈✳ ▲♦❞❞❡r✱ ❛♥❞ ❘✳ ❏❛♥s❡♥✱ ✏❚✉♥♥❡❧✐♥❣ ♠❛❣♥❡t♦r❡s✐st❛♥❝❡ ✇✐t❤ ♣♦s✐t✐✈❡ ❛♥❞ ♥❡❣❛t✐✈❡ s✐❣♥ ✐♥ la0.67sr0.33mno3/srtio3/Co