Profiles of oxygen and titanium point defects in ferromagnetic
TiO2 films

J 2024

Profiles of oxygen and titanium point defects in ferromagnetic TiO2 films

TRAN, Quynh Nhu Thi, Martin FRIÁK, Ivana MIHÁLIKOVÁ, Michal KIABA, Hoa Hong NGUYEN et. al.

Basic information

Original name

Profiles of oxygen and titanium point defects in ferromagnetic TiO2 films

Authors

TRAN, Quynh Nhu Thi (704 Viet Nam, belonging to the institution), Martin FRIÁK (203 Czech Republic, belonging to the institution), Ivana MIHÁLIKOVÁ (703 Slovakia, belonging to the institution), Michal KIABA (703 Slovakia, belonging to the institution) and Hoa Hong NGUYEN (250 France, guarantor, belonging to the institution)

Edition

Journal of Physics D: Applied Physics, IOP Publishing Ltd, 2024, 0022-3727

Other information

Language

English

Type of outcome

Článek v odborném periodiku

Field of Study

10302 Condensed matter physics

Country of publisher

United Kingdom of Great Britain and Northern Ireland

Confidentiality degree

není předmětem státního či obchodního tajemství

References:

URL

Impact factor

Impact factor: 3.400 in 2022

Organization unit

Faculty of Science

DOI

http://dx.doi.org/10.1088/1361-6463/ad3767

UT WoS

001196338000001

Keywords in English

vacancies; defects; ferromagnetic; DMSO; spintronics

Abstract

V originále

Experimentally it is shown that without any oxygen manipulation for TiO2, a strong room temperature ferromagnetism could be expected only in ultra-thin films, with the ideal thickness below 100 nm. Both bulks and nano-powders of TiO2 are diamagnetic, indicating that the surface and its nano-sublayers play very important roles in tailoring the magnetic properties in this type of compound. To shed a new light on the defect-related magnetism in the typical case of anatase TiO2 surfaces, we have performed a series of quantum-mechanical calculations for TiO2 slabs containing Ti or O vacancies in different distances from the (001) surface. The lowest formation energies were obtained for the Ti vacancies in the first sub-surface layer and the O vacancies within the surface. The computed magnetic states reflect complicated structural relaxations of atoms influenced by both the surface and vacant atomic positions. O atoms cannot contribute much to magnetic moment when Ti vacancies are isolated and far from the surface. Ti vacancies in TiO2 are only metastable. The formation energy of Ti interstitials is lower than for Ti vacancies since high-temperature annealing, especially with a lot of O2 available that would fill up O-related defects, and as a result, eliminate most of Ti vacancies. Lower temperatures, less O2, and shorter exposure times may enable not only partial elimination of Ti vacancies but also can facilitate their diffusion into different states of aggregations. In the ferromagnetic films (i.e. thin films below 100 nm), it looks like that the O atoms are located closer to the Ti vacancies.

Links

EH22_008/0004572, research and development project

Name: Kvantové materiály pro aplikace v udržitelných technologiích

GA22-21547S, research and development project

Name: Původ feromagnetismu při pokojové teplotě v tenkých vrstvách nedopovaných polovodičových oxidů typu d0

Investor: Czech Science Foundation

90110, large research infrastructures

Name: CzechNanoLab

90140, large research infrastructures

Name: e-INFRA CZ

Citovat

TRAN, Quynh Nhu Thi, Martin FRIÁK, Ivana MIHÁLIKOVÁ, Michal KIABA and Hoa Hong NGUYEN. Profiles of oxygen and titanium point defects in ferromagnetic TiO2 films. Journal of Physics D: Applied Physics. IOP Publishing Ltd, 2024, vol. 57, No 26, p. 1-8. ISSN 0022-3727. Available from: https://dx.doi.org/10.1088/1361-6463/ad3767.

@article{2391030,
   author = {Tran, Quynh Nhu Thi and Friák, Martin and Miháliková, Ivana and Kiaba, Michal and NGUYEN, Hoa Hong},
   article_number = {26},
   doi = {http://dx.doi.org/10.1088/1361-6463/ad3767},
   keywords = {vacancies; defects; ferromagnetic; DMSO; spintronics},
   language = {eng},
   issn = {0022-3727},
   journal = {Journal of Physics D: Applied Physics},
   title = {Profiles of oxygen and titanium point defects in ferromagnetic TiO2 films},
   url = {https://iopscience.iop.org/article/10.1088/1361-6463/ad3767},
   volume = {57},
   year = {2024}
}

TY  - JOUR
ID  - 2391030
AU  - Tran, Quynh Nhu Thi - Friák, Martin - Miháliková, Ivana - Kiaba, Michal - NGUYEN, Hoa Hong
PY  - 2024
TI  - Profiles of oxygen and titanium point defects in ferromagnetic TiO2 films
JF  - Journal of Physics D: Applied Physics
VL  - 57
IS  - 26
SP  - 1-8
EP  - 1-8
PB  - IOP Publishing Ltd
SN  - 00223727
KW  - vacancies
KW  - defects
KW  - ferromagnetic
KW  - DMSO
KW  - spintronics
UR  - https://iopscience.iop.org/article/10.1088/1361-6463/ad3767
N2  - Experimentally it is shown that without any oxygen manipulation for TiO2, a strong room temperature ferromagnetism could be expected only in ultra-thin films, with the ideal thickness below 100 nm. Both bulks and nano-powders of TiO2 are diamagnetic, indicating that the surface and its nano-sublayers play very important roles in tailoring the magnetic properties in this type of compound. To shed a new light on the defect-related magnetism in the typical case of anatase TiO2 surfaces, we have performed a series of quantum-mechanical calculations for TiO2 slabs containing Ti or O vacancies in different distances from the (001) surface. The lowest formation energies were obtained for the Ti vacancies in the first sub-surface layer and the O vacancies within the surface. The computed magnetic states reflect complicated structural relaxations of atoms influenced by both the surface and vacant atomic positions. O atoms cannot contribute much to magnetic moment when Ti vacancies are isolated and far from the surface. Ti vacancies in TiO2 are only metastable. The formation energy of Ti interstitials is lower than for Ti vacancies since high-temperature annealing, especially with a lot of O2 available that would fill up O-related defects, and as a result, eliminate most of Ti vacancies. Lower temperatures, less O2, and shorter exposure times may enable not only partial elimination of Ti vacancies but also can facilitate their diffusion into different states of aggregations. In the ferromagnetic films (i.e. thin films below 100 nm), it looks like that the O atoms are located closer to the Ti vacancies.
ER  -

TRAN, Quynh Nhu Thi, Martin FRIÁK, Ivana MIHÁLIKOVÁ, Michal KIABA and Hoa Hong NGUYEN. Profiles of oxygen and titanium point defects in ferromagnetic TiO2 films. \textit{Journal of Physics D: Applied Physics}. IOP Publishing Ltd, 2024, vol.~57, No~26, p.~1-8. ISSN~0022-3727. Available from: https://dx.doi.org/10.1088/1361-6463/ad3767.

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