Decay in spin diffusion length with temperature in organic semiconductors: An insight of possible mechanisms

S. Majumdar (Corresponding Author), Himadri Majumdar

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Abstract

This article presents a comparison of spin transport mechanism in two π-conjugated organic polymers namely, regiorandom and regioregular poly (3-hexyl thiophenes) with same elemental composition but different regioregularity of the constituent atoms leading to different crystallinity and charge carrier mobility. Spin-valve devices made with both polymers show substantial low temperature giant magnetoresistance (GMR) response. However, the GMR signal decreases drastically at higher temperatures where charge carrier mobility is higher. Our results suggest that in both the polymers spin diffusion length at low temperature is almost similar, but, temperature dependence of spin diffusion length is greater in the disordered polymer compared to the more structured one. Comprehensive analysis of our experimental data suggest that at low temperature, in the VRH hopping regime (5–50 K), spin relaxation due to hyperfine interaction and Elliot-Yafet momentum scattering is the dominant spin relaxation mechanism while in the thermally activated regime Dyakonov–Perel mechanism contribution becomes significant. However, mobility dependence of spin scattering rate in both systems differ from traditional Dyakonov–Perel model signifying that there are coexisting contributions from several spin scattering effects present in the system. Proper understanding and careful modification of spin–orbit coupling in organic semiconductors can be very useful for organic based spin devices.
Original languageEnglish
Pages (from-to)26-30
Number of pages5
JournalSynthetic Metals
Volume173
DOIs
Publication statusPublished - 2013
MoE publication typeA1 Journal article-refereed
Event4th International Meeting on Spins in Organic Semiconductors 2012 - London, United Kingdom
Duration: 10 Sep 201213 Sep 2012

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Semiconducting organic compounds
organic semiconductors
diffusion length
decay
Giant magnetoresistance
Polymers
Carrier mobility
Scattering
Charge carriers
Temperature
temperature
Thiophenes
polymers
Organic polymers
carrier mobility
Conjugated polymers
Thiophene
charge carriers
Momentum
scattering

Keywords

  • giant magnetoresistance
  • organic semiconductors
  • organic spintronics
  • spin transport and relaxation
  • thin film electronic devices

Cite this

@article{96f767ff6f964dd18e18a2222b217a3c,
title = "Decay in spin diffusion length with temperature in organic semiconductors: An insight of possible mechanisms",
abstract = "This article presents a comparison of spin transport mechanism in two π-conjugated organic polymers namely, regiorandom and regioregular poly (3-hexyl thiophenes) with same elemental composition but different regioregularity of the constituent atoms leading to different crystallinity and charge carrier mobility. Spin-valve devices made with both polymers show substantial low temperature giant magnetoresistance (GMR) response. However, the GMR signal decreases drastically at higher temperatures where charge carrier mobility is higher. Our results suggest that in both the polymers spin diffusion length at low temperature is almost similar, but, temperature dependence of spin diffusion length is greater in the disordered polymer compared to the more structured one. Comprehensive analysis of our experimental data suggest that at low temperature, in the VRH hopping regime (5–50 K), spin relaxation due to hyperfine interaction and Elliot-Yafet momentum scattering is the dominant spin relaxation mechanism while in the thermally activated regime Dyakonov–Perel mechanism contribution becomes significant. However, mobility dependence of spin scattering rate in both systems differ from traditional Dyakonov–Perel model signifying that there are coexisting contributions from several spin scattering effects present in the system. Proper understanding and careful modification of spin–orbit coupling in organic semiconductors can be very useful for organic based spin devices.",
keywords = "giant magnetoresistance, organic semiconductors, organic spintronics, spin transport and relaxation, thin film electronic devices",
author = "S. Majumdar and Himadri Majumdar",
year = "2013",
doi = "10.1016/j.synthmet.2013.02.002",
language = "English",
volume = "173",
pages = "26--30",
journal = "Synthetic Metals",
issn = "0379-6779",
publisher = "Elsevier",

}

TY - JOUR

T1 - Decay in spin diffusion length with temperature in organic semiconductors

T2 - An insight of possible mechanisms

AU - Majumdar, S.

AU - Majumdar, Himadri

PY - 2013

Y1 - 2013

N2 - This article presents a comparison of spin transport mechanism in two π-conjugated organic polymers namely, regiorandom and regioregular poly (3-hexyl thiophenes) with same elemental composition but different regioregularity of the constituent atoms leading to different crystallinity and charge carrier mobility. Spin-valve devices made with both polymers show substantial low temperature giant magnetoresistance (GMR) response. However, the GMR signal decreases drastically at higher temperatures where charge carrier mobility is higher. Our results suggest that in both the polymers spin diffusion length at low temperature is almost similar, but, temperature dependence of spin diffusion length is greater in the disordered polymer compared to the more structured one. Comprehensive analysis of our experimental data suggest that at low temperature, in the VRH hopping regime (5–50 K), spin relaxation due to hyperfine interaction and Elliot-Yafet momentum scattering is the dominant spin relaxation mechanism while in the thermally activated regime Dyakonov–Perel mechanism contribution becomes significant. However, mobility dependence of spin scattering rate in both systems differ from traditional Dyakonov–Perel model signifying that there are coexisting contributions from several spin scattering effects present in the system. Proper understanding and careful modification of spin–orbit coupling in organic semiconductors can be very useful for organic based spin devices.

AB - This article presents a comparison of spin transport mechanism in two π-conjugated organic polymers namely, regiorandom and regioregular poly (3-hexyl thiophenes) with same elemental composition but different regioregularity of the constituent atoms leading to different crystallinity and charge carrier mobility. Spin-valve devices made with both polymers show substantial low temperature giant magnetoresistance (GMR) response. However, the GMR signal decreases drastically at higher temperatures where charge carrier mobility is higher. Our results suggest that in both the polymers spin diffusion length at low temperature is almost similar, but, temperature dependence of spin diffusion length is greater in the disordered polymer compared to the more structured one. Comprehensive analysis of our experimental data suggest that at low temperature, in the VRH hopping regime (5–50 K), spin relaxation due to hyperfine interaction and Elliot-Yafet momentum scattering is the dominant spin relaxation mechanism while in the thermally activated regime Dyakonov–Perel mechanism contribution becomes significant. However, mobility dependence of spin scattering rate in both systems differ from traditional Dyakonov–Perel model signifying that there are coexisting contributions from several spin scattering effects present in the system. Proper understanding and careful modification of spin–orbit coupling in organic semiconductors can be very useful for organic based spin devices.

KW - giant magnetoresistance

KW - organic semiconductors

KW - organic spintronics

KW - spin transport and relaxation

KW - thin film electronic devices

U2 - 10.1016/j.synthmet.2013.02.002

DO - 10.1016/j.synthmet.2013.02.002

M3 - Article

VL - 173

SP - 26

EP - 30

JO - Synthetic Metals

JF - Synthetic Metals

SN - 0379-6779

ER -