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Title: Coupled Lattice Polarization and Ferromagnetism in Multiferroic NiTiO 3 Thin Films

Abstract

Polarization-induced weak ferromagnetism (WFM) was demonstrated a few years back in LiNbO3-type compounds, MTiO3 (M = Fe, Mn, Ni). Although the coexistence of ferroelectric polarization and ferromagnetism has been demonstrated in this rare multiferroic family before, first in bulk FeTiO3, then in thin-film NiTiO3, the coupling of the two order parameters has not been confirmed Here, we report the stabilization of polar, ferromagnetic NiTiO3 by oxide epitaxy on a LiNbO3 substrate utilizing tensile strain and demonstrate the theoretically predicted coupling between its polarization and ferromagnetism by X-ray magnetic circular dichroism under applied fields. The experimentally observed direction of ferroic ordering in the film is supported by simulations using the phase-field approach. Our work validates symmetry-based criteria and first-principles calculations of the coexistence of ferroelectricity and WFM in MTiO3 transition metal titanates crystallizing in the LiNbO3 structure. It also demonstrates the applicability of epitaxial strain as a viable alternative to high-pressure crystal growth to stabilize metastable materials and a valuable tuning parameter to simultaneously control two ferroic order parameters to create a multiferroic. Multiferroic NiTiO3 has potential applications in spintronics where ferroic switching is used, such as new four-stage memories and electromagnetic switches.

Authors:
ORCiD logo; ; ;  [1]; ; ORCiD logo;  [2]; ORCiD logo [3];  [2]; ;
  1. Imaging and Chemical Analysis Laboratory, Montana State University, Bozeman, Montana 59717, United States
  2. Materials Science Division, Argonne National Laboratory, Argonne, Illinois 60439, United States; Department of Materials Science and Engineering, KAIST, Daejeon 34141, Republic of Korea
  3. Department of Materials Science and Engineering, KAIST, Daejeon 34141, Republic of Korea
Publication Date:
Research Org.:
Argonne National Lab. (ANL), Argonne, IL (United States)
Sponsoring Org.:
USDOE Office of Science - Office of Basic Energy Sciences - Materials Sciences and Engineering Division; USDOE Office of Science - Office of Biological and Environmental Research
OSTI Identifier:
1373099
DOE Contract Number:
AC02-06CH11357
Resource Type:
Journal Article
Resource Relation:
Journal Name: ACS Applied Materials and Interfaces; Journal Volume: 9; Journal Issue: 26
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; epitaxial film; epitaxial strain; ferroic properties; multiferroic; nickel titanate

Citation Formats

Varga, Tamas, Droubay, Timothy C., Kovarik, Libor, Nandasiri, Manjula I., Shutthanandan, Vaithiyalingam, Hu, Dehong, Kim, Bumsoo, Jeon, Seokwoo, Hong, Seungbum, Li, Yulan, and Chambers, Scott A. Coupled Lattice Polarization and Ferromagnetism in Multiferroic NiTiO 3 Thin Films. United States: N. p., 2017. Web. doi:10.1021/acsami.7b04481.
Varga, Tamas, Droubay, Timothy C., Kovarik, Libor, Nandasiri, Manjula I., Shutthanandan, Vaithiyalingam, Hu, Dehong, Kim, Bumsoo, Jeon, Seokwoo, Hong, Seungbum, Li, Yulan, & Chambers, Scott A. Coupled Lattice Polarization and Ferromagnetism in Multiferroic NiTiO 3 Thin Films. United States. doi:10.1021/acsami.7b04481.
Varga, Tamas, Droubay, Timothy C., Kovarik, Libor, Nandasiri, Manjula I., Shutthanandan, Vaithiyalingam, Hu, Dehong, Kim, Bumsoo, Jeon, Seokwoo, Hong, Seungbum, Li, Yulan, and Chambers, Scott A. Thu . "Coupled Lattice Polarization and Ferromagnetism in Multiferroic NiTiO 3 Thin Films". United States. doi:10.1021/acsami.7b04481.
@article{osti_1373099,
title = {Coupled Lattice Polarization and Ferromagnetism in Multiferroic NiTiO 3 Thin Films},
author = {Varga, Tamas and Droubay, Timothy C. and Kovarik, Libor and Nandasiri, Manjula I. and Shutthanandan, Vaithiyalingam and Hu, Dehong and Kim, Bumsoo and Jeon, Seokwoo and Hong, Seungbum and Li, Yulan and Chambers, Scott A.},
abstractNote = {Polarization-induced weak ferromagnetism (WFM) was demonstrated a few years back in LiNbO3-type compounds, MTiO3 (M = Fe, Mn, Ni). Although the coexistence of ferroelectric polarization and ferromagnetism has been demonstrated in this rare multiferroic family before, first in bulk FeTiO3, then in thin-film NiTiO3, the coupling of the two order parameters has not been confirmed Here, we report the stabilization of polar, ferromagnetic NiTiO3 by oxide epitaxy on a LiNbO3 substrate utilizing tensile strain and demonstrate the theoretically predicted coupling between its polarization and ferromagnetism by X-ray magnetic circular dichroism under applied fields. The experimentally observed direction of ferroic ordering in the film is supported by simulations using the phase-field approach. Our work validates symmetry-based criteria and first-principles calculations of the coexistence of ferroelectricity and WFM in MTiO3 transition metal titanates crystallizing in the LiNbO3 structure. It also demonstrates the applicability of epitaxial strain as a viable alternative to high-pressure crystal growth to stabilize metastable materials and a valuable tuning parameter to simultaneously control two ferroic order parameters to create a multiferroic. Multiferroic NiTiO3 has potential applications in spintronics where ferroic switching is used, such as new four-stage memories and electromagnetic switches.},
doi = {10.1021/acsami.7b04481},
journal = {ACS Applied Materials and Interfaces},
number = 26,
volume = 9,
place = {United States},
year = {Thu Jun 22 00:00:00 EDT 2017},
month = {Thu Jun 22 00:00:00 EDT 2017}
}
  • Polarization-induced weak ferromagnetism has been predicted recently in LiNbO3-type MTiO3 (M = Fe, Mn, Ni). While coexisting ferroelectric polarization and ferromagnetism have been demonstrated in this family before, first in bulk FeTiO3, then in thin-film NiTiO3, the coupling of the two order parameters has not been confirmed. Here we report the stabilization of polar, ferromagnetic NiTiO3 by oxide epitaxy on LiNbO3 substrate utilizing tensile strain, and demonstrate the theory-predicted coupling between its polarization and ferromagnetism by x-ray magnetic circular dichroism under applied fields. The experimentally observed direction of ferroic ordering in the film is supported by simulation using phase-field approach.more » Our work validates symmetry-based criteria and first-principles calculations of the coexistence of ferroelectricity and weak ferromagnetism in MTiO3 transition metal titanates crystallizing in the LiNbO3 structure. It also demonstrates the applicability of epitaxial strain as a viable alternative to high-pressure crystal growth to stabilize metastable materials, and a valuable tuning parameter to simultaneously control two ferroic order parameters to create a multiferroic.« less
  • We report the magnetic and structural characteristics of epitaxial NiTiO 3 films grown by pulsed laser deposition that are isostructural with acentric LiNbO 3 (space group R3c). Optical second harmonic generation and magnetometry demonstrate lattice polarization at room temperature and weak ferromagnetism below 250 K, respectively. These results appear to be consistent with earlier predictions from first-principles calculations of the coexistence of ferroelectricity and weak ferromagnetism in a series of transition metal titanates crystallizing in the LiNbO 3 structure. This acentric form of NiTiO 3 is believed to be one of the rare examples of ferroelectrics exhibiting weak ferromagnetism generatedmore » by a Dzyaloshinskii-Moriya interaction.« less
  • Polarization-induced weak ferromagnetism has been predicted a few years back in perovskite MTiO 3 (M = Fe, Mn, and Ni). We set out to stabilize this metastable perovskite structure by growing NiTiO 3 epitaxially on different substrates and to investigate the dependence of polar and magnetic properties on strain. Epitaxial NiTiO 3 films were deposited on Al 2 O 3 , Fe 2 O 3 , and LiNbO 3 substrates by pulsed laser deposition and characterized using several techniques. The effect of substrate choice on lattice strain, film structure, and physical properties was investigated. Our structural data from X-ray diffractionmore » and electron microscopy shows that substrate-induced strain has a marked effect on the structure and crystalline quality of the films. Physical property measurements reveal a dependence of the weak ferromagnetism and lattice polarization on strain and highlight our ability to control the ferroic properties in NiTiO 3 thin films by the choice of substrate. Our results are also consistent with the theoretical prediction that the ferromagnetism in acentric NiTiO 3 is polarization induced. From the substrates studied here, the perovskite substrate LiNbO 3 proved to be the most promising one for strong multiferroism.« less
  • Multiferroic (Bi{sub 0.90}La{sub 0.10})(Fe{sub 0.95}Mn{sub 0.05})O{sub 3} (BLFMO) thin films were deposited on SrRuO{sub 3} (SRO) buffered Pt/TiO{sub 2}/SiO{sub 2}/Si(100) substrates with variable buffer layer thicknesses by using off-axis radio frequency sputtering. The orientation of BLFMO thin films is dependent on the SRO buffer layer thickness, which leads to a change in ferroelectric behavior. Due to the low leakage currents arising from the orientation change in association with the variation in SRO buffer layer thickness and the La and Mn codoping, well saturated P-E hysteresis loops (2P{sub r}approx210.0 muC/cm{sup 2} and 2E{sub c}approx525.5 kV/cm) are shown for the (111)-oriented BLFMOmore » thin film at room temperature and 1 kHz. It also demonstrates little ferroelectric fatigue on 10{sup 9} switching cycles. Moreover, the BLFMO thin film exhibits the enhanced magnetic behavior as compared to pure BFO thin films, due to the canting of antiferromagnetically ordered spins.« less
  • Multiferroic composite thin films consisting of CoFe{sub 2}O{sub 4} (CFO) and Pb(Zr{sub 0.52}Ti{sub 0.48})O{sub 3} (PZT) layers were deposited through a combined route of rf magnetron sputtering and sol gel on Pt(111)/TiO{sub 2}/SiO{sub 2}/Si substrates. The coupling effects in the bilayered thin film were studied by looking at the relationships among the crystallite orientation, magnetic behavior, and the in-plane residual stress. Phase selective residual stress analysis conducted by using x-ray method demonstrated a close correlation between the stress imposed on the PZT layer and its texture. A change in the PZT layer orientation from (111) to (010) with the increasingmore » layer thickness was observed in the multiferroic thin film as the system changes from an interface energy minimizing texture to a strain energy density minimizing texture. The CFO phase in the multiferroic thin films was preferably oriented in the (111) orientation. However, there is a change in magnetization as well as coercivity of the multiferroic thin films when the top PZT layer was varied in thickness. A close correlation between the magnetization and the in-plane stress in the CFO bottom layer imposed by the PZT film thickness was observed.« less