Organic spin valves: effect of magnetic impurities on the spin transport properties of polymer spacers

Sayani Majumdar (Corresponding Author), Himadri S. Majumdar, Reino Laiho, Ronald Oesterbacka

Research output: Contribution to journalArticleScientificpeer-review

24 Citations (Scopus)

Abstract

We report the effect of magnetic impurities in the spacer layer of polymeric spin valves (PSV) with the sandwich configuration of La0.67Sr0.33MnO3 (LSMO)/π-conjugated polymer regio-random poly(3-hexyl thiophene)/cobalt (Co), showing giant magnetoresistance (GMR) response. Different deposition rates of Co at the top electrode resulted in two types of devices: one with lower device resistance and linear current–voltage (I–V) characteristics and the other with very low inclusion of Co and exhibiting higher device resistance and nonlinear I–V characteristics. We observed an asymmetric dc bias dependence of magnetoresistance (MR) in devices with more Co inclusion, while for the other type of device, bias dependence was more symmetric. At higher bias, %MR of both types of device showed no significant difference (5–10%), but at low dc bias it ranged between 50 and 160% MR. This can be attributed to the higher tunneling probability of spin-polarized carriers from one ferromagnetic electrode to the other. Magnetic tunnel junction-like features are observed in the devices with greater Co inclusions. Anomalous MR peaks were also observed in these devices and their origin was explained in terms of presence of additional scattering centers around the included metal ions and increased spin relaxation due to high magnetic anisotropy in the system. Both types of PSVs showed a monotonic decrease in MR with temperature at high bias currents.
Original languageEnglish
Article number013022
JournalNew Journal of Physics
Volume11
DOIs
Publication statusPublished - 2009
MoE publication typeA1 Journal article-refereed

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spacers
transport properties
impurities
polymers
cobalt
inclusions
electrodes
thiophenes
tunnel junctions
metal ions
anisotropy
configurations
scattering

Cite this

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title = "Organic spin valves: effect of magnetic impurities on the spin transport properties of polymer spacers",
abstract = "We report the effect of magnetic impurities in the spacer layer of polymeric spin valves (PSV) with the sandwich configuration of La0.67Sr0.33MnO3 (LSMO)/π-conjugated polymer regio-random poly(3-hexyl thiophene)/cobalt (Co), showing giant magnetoresistance (GMR) response. Different deposition rates of Co at the top electrode resulted in two types of devices: one with lower device resistance and linear current–voltage (I–V) characteristics and the other with very low inclusion of Co and exhibiting higher device resistance and nonlinear I–V characteristics. We observed an asymmetric dc bias dependence of magnetoresistance (MR) in devices with more Co inclusion, while for the other type of device, bias dependence was more symmetric. At higher bias, {\%}MR of both types of device showed no significant difference (5–10{\%}), but at low dc bias it ranged between 50 and 160{\%} MR. This can be attributed to the higher tunneling probability of spin-polarized carriers from one ferromagnetic electrode to the other. Magnetic tunnel junction-like features are observed in the devices with greater Co inclusions. Anomalous MR peaks were also observed in these devices and their origin was explained in terms of presence of additional scattering centers around the included metal ions and increased spin relaxation due to high magnetic anisotropy in the system. Both types of PSVs showed a monotonic decrease in MR with temperature at high bias currents.",
author = "Sayani Majumdar and Majumdar, {Himadri S.} and Reino Laiho and Ronald Oesterbacka",
year = "2009",
doi = "10.1088/1367-2630/11/1/013022",
language = "English",
volume = "11",
journal = "New Journal of Physics",
issn = "1367-2630",
publisher = "Institute of Physics IOP",

}

Organic spin valves: effect of magnetic impurities on the spin transport properties of polymer spacers. / Majumdar, Sayani (Corresponding Author); Majumdar, Himadri S.; Laiho, Reino; Oesterbacka, Ronald.

In: New Journal of Physics, Vol. 11, 013022, 2009.

Research output: Contribution to journalArticleScientificpeer-review

TY - JOUR

T1 - Organic spin valves: effect of magnetic impurities on the spin transport properties of polymer spacers

AU - Majumdar, Sayani

AU - Majumdar, Himadri S.

AU - Laiho, Reino

AU - Oesterbacka, Ronald

PY - 2009

Y1 - 2009

N2 - We report the effect of magnetic impurities in the spacer layer of polymeric spin valves (PSV) with the sandwich configuration of La0.67Sr0.33MnO3 (LSMO)/π-conjugated polymer regio-random poly(3-hexyl thiophene)/cobalt (Co), showing giant magnetoresistance (GMR) response. Different deposition rates of Co at the top electrode resulted in two types of devices: one with lower device resistance and linear current–voltage (I–V) characteristics and the other with very low inclusion of Co and exhibiting higher device resistance and nonlinear I–V characteristics. We observed an asymmetric dc bias dependence of magnetoresistance (MR) in devices with more Co inclusion, while for the other type of device, bias dependence was more symmetric. At higher bias, %MR of both types of device showed no significant difference (5–10%), but at low dc bias it ranged between 50 and 160% MR. This can be attributed to the higher tunneling probability of spin-polarized carriers from one ferromagnetic electrode to the other. Magnetic tunnel junction-like features are observed in the devices with greater Co inclusions. Anomalous MR peaks were also observed in these devices and their origin was explained in terms of presence of additional scattering centers around the included metal ions and increased spin relaxation due to high magnetic anisotropy in the system. Both types of PSVs showed a monotonic decrease in MR with temperature at high bias currents.

AB - We report the effect of magnetic impurities in the spacer layer of polymeric spin valves (PSV) with the sandwich configuration of La0.67Sr0.33MnO3 (LSMO)/π-conjugated polymer regio-random poly(3-hexyl thiophene)/cobalt (Co), showing giant magnetoresistance (GMR) response. Different deposition rates of Co at the top electrode resulted in two types of devices: one with lower device resistance and linear current–voltage (I–V) characteristics and the other with very low inclusion of Co and exhibiting higher device resistance and nonlinear I–V characteristics. We observed an asymmetric dc bias dependence of magnetoresistance (MR) in devices with more Co inclusion, while for the other type of device, bias dependence was more symmetric. At higher bias, %MR of both types of device showed no significant difference (5–10%), but at low dc bias it ranged between 50 and 160% MR. This can be attributed to the higher tunneling probability of spin-polarized carriers from one ferromagnetic electrode to the other. Magnetic tunnel junction-like features are observed in the devices with greater Co inclusions. Anomalous MR peaks were also observed in these devices and their origin was explained in terms of presence of additional scattering centers around the included metal ions and increased spin relaxation due to high magnetic anisotropy in the system. Both types of PSVs showed a monotonic decrease in MR with temperature at high bias currents.

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DO - 10.1088/1367-2630/11/1/013022

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