Structural phase transition and enhanced ferroelectricity in Bi(Fe1 − xMnx)O3 thin films deposited by pulsed laser deposition

doi:10.1016/j.tsf.2015.10.017

Thin Solid Films

Volume 594, Part A, 2 November 2015, Pages 80-87

https://doi.org/10.1016/j.tsf.2015.10.017 Get rights and content

Highlights

•
The BiFeO₃ and BiMnO₃ reveal a rhombohedral and monoclinic structure respectively.
•
Proposed a phase diagram of Bi(Fe_1 − xMn_x)O₃ thin films
•
BiFe_0.5Mn_0.5O₃ film exhibits high dielectric constant and low leakage current.
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Coexistence of two-phase shows enhanced ferroelectric properties.

Abstract

In this study, BiFeO₃ (BFO), BiFe_0.5Mn_0.5O₃ (BFMO) and BiMnO₃ (BMO) thin films were fabricated on LaNiO₃ (LNO) coated Si(100) substrates by the pulsed laser deposition method. LNO buffer layer provides epitaxial (l00) growth of pervoskite BFO, BFMO, and BMO thin films. The Raman spectra showed that BFO structure is best described as rhombohedral (R3c), and that doping with Mn causes a substantial modification, Jahn–Teller distortion to octahedral accompanied by structural transition toward mixed phase of orthorhombic and rhombohedral. Field emission scanning electron microscope and atomic force microscope images revealed that the average grain size of the BMO thin film is larger than that of BFO and BFMO thin films. It is also observed that BFMO thin film exhibits improved ferroelectric property compared to pure BFO and BMO films. This enhancement of ferroelectric properties could be due to the Jahn–Teller distortion of octahedral in addition to low defects and oxygen vacancies in BFMO films. The leakage behavior of BFO film endures a transition from an Ohmic conduction to space charge limited conduction with increasing electric field, which was associated with the free carriers trapped by the oxygen vacancies. On the contrary, the leakage currents in BFMO and BMO films were found to be subject to trap-free Ohmic conduction.

Introduction

Multiferroic materials, showing co-existence of two or all three ferroic properties, namely, ferroelectricity, ferromagnetism, and ferroelasticity in a single phase, have been studied extensively during the last decade because they offer a wide range of potential applications in memory devices and spintronics [1], [2]. Among all the identified multiferroics BiFeO₃ (BFO) and BiMnO₃ (BMO) are well-known candidates for memory devices. BFO, having a distorted rhombohedral structure (space group R3c), shows a G-type antiferromagnetic order (T_N ~ 643 K) and ferroelectricity (T_C ~ 1103 K) at room temperature [3], [4]. It is commonly accepted that the ferroelectricity of BFO is due to 6s² lone-pair distortions of Bi^3 + at A-site, whereas the residual moment of the Fe^3 + (B-site) spin structure could result in very weak ferromagnetism. On the other hand, BMO is a monoclinically distorted perovskite and it undergoes a structural phase transition to tetragonal symmetry at 760 K. BMO exhibits ferroelectricity up to 450 K and ferromagnetism with a Curie temperature of 105 K [5]. However, high leakage current in BFO film, because of oxygen vacancies and the existence of various oxidation states of Fe ion (Fe^2 + to Fe^3 + state), has become major obstacles for potential feasible applications [6]. Singh et al. have reported that the Fe site substitution of BFO by Mn atoms showed an enhancement of ferroelectric properties [7], [8]. As both BFO and BMO exhibit distinct ferroelectric and magnetic properties, it is expected therefore that the study of BiFe_1 − xMn_xO₃ series provides a unique way to find an optimized multiferroic. Bulk studies of the BiFe_1 − xMn_xO₃ series have usually been restricted to lower Mn concentrations (x < 0.3). Bulk BiFe_0.5Mn_0.5O₃ (BFMO) is not yet available because phases containing a high Mn concentration are metastable, and single phase powders cannot be fabricated unless high pressures are used [9]. Apart from this, the reason for particularly choosing BiFe₁ _− xMn_xO₃ is that there is a possibility of morphotropic phase boundary which favors enhancement in ferroelectric and dielectric effects [10].

To the best of our knowledge, there is no report on comparative study of BFO, BFMO and BMO thin films fabricated on LaNiO₃ (LNO) coated Si(100) by pulsed laser deposition (PLD). Among various thin film deposition techniques, PLD has been recognized as a promising, versatile technique for the deposition of BFO, BFMO and BMO thin films and other metal oxides at high deposition rate. Moreover, PLD has an added advantage of being a non-equilibrium process. Epitaxial growth of these compounds presents a substantial challenge for two reasons. First, the volatility of the bismuth makes it difficult to achieve high quality thin films with the same stoichiometries as a target. Second, the desire for solely Mn in the BiMnO₃ thin films means that the oxygen partial pressure must be controlled during growth and cooling. In addition, because there is no ambient pressure phase, special care needs to be taken to ensure a proper homogenization of the target, without compromising the Bi content [11]. However, there are several reports displaying the growth of BFO film on LNO coated Si by PLD, showing improved ferroelectric and magnetic properties [12]. Earlier we reported the deposition of thin films of various oxide materials like BaRuO₃ [13] and RNiO₃ [14] via the PLD technique. The main aim of the present study is to investigate and compare the structural and electrical behavior of pulsed laser deposited thin films of BFO, BFMO and BMO on LNO coated Si, and provide a phase diagram regarding structural change in Bi(Fe_1 − xMn_x)O₃ thin films with Mn content.

Section snippets

Experimental procedure

Nanostructured Bi(Fe_1 − xMn_x)O₃ (x = 0, 0.5, 1) thin films were synthesized on LNO coated Si(100) using the PLD technique. The targets of BFO, BFMO and BMO, respectively, were prepared by the conventional solid state reaction method. High purity starting oxide powders of Bi₂O₃, Fe₂O₃ and MnO₂ were weighed stoichiometrically, thoroughly mixed with the addition of alcohol, grind, dried and then calcined at 600 °C for 8 h. After calcinations, the powder was again grind and compacted in the form of

Structural properties

Fig. 1 shows the room temperature X-ray diffraction (XRD) plots of BFO/LNO, BFMO/LNO and BMO/LNO films on Si substrates and corresponding values of various parameters calculated from XRD analysis are mentioned in Table 2. The average crystallite size (L) in the thin films was determined using the formula reported elsewhere [15]. These values are ~ 27, 33 and 46 nm for BFO, BFMO and BMO thin films, respectively. The LNO bottom electrode, acting as a seed layer, owing to a perovskite structure,

Conclusions

Epitaxial thin films of BFO, BFMO and BMO were grown on Si(100) coated with conducting oxide LNO by pulsed laser deposition. Smooth and closely packed surfaces with grain size of 32–81 nm were observed. A Raman spectrum indicates that BFO thin film possesses a rhombohedral structure (R3c), whereas BMO film shows a monoclinic (C_2/c) structure. A morphological study reveals that the grain size in BiFe_1 − xMn_xO₃ thin film increases with the increase in Mn concentration. Mn doping causes a substantial

Acknowledgments

The financial support provided by the Defence Research and Development Organization (DRDO), India under ER & IPR with Reference No. ERIP/ER/1100406/M/01/1439 is highly acknowledged.

References (35)

C. Bhardwaj et al.
Pulsed laser deposition and characterization of highly tunable (1 − x)Ba(Zr_0.2Ti_0.8)O₃–x(Ba_0.7Ca_0.3)TiO₃ thin films grown on LaNiO₃/Si substrate
J. Phys. Chem. Solids
(2013)
H.S. Zhang et al.
Comparative surface and nano-tribological characteristics of nocomposite diamond-like carbon thin films doped by silver
Appl. Surf. Sci.
(2008)
F.D. Hardcastle et al.
The molecular structure of bismuth oxide by Raman spectroscopy
J. Solid State Chem.
(1992)
M. Azuma et al.
Magnetic and structural properties of BiFe_1 − xMnxO₃
J. Magn. Magn. Mater.
(2007)
G. Dong et al.
Optimization of the multiferroic BiFeO₃thinfilms by divalent ion (Mn, Ni) co-doping at B-sites
Mater. Lett.
(2014)
W. Eerenstein et al.
Multiferroic and magnetoelectric materials
Nature
(2006)
R. Ramesh et al.
Multiferroics: progress and prospects in thin films
Nat. Mater.
(2007)
G. Catalan et al.
Physics and applications of bismuth ferrite
Adv. Mater.
(2009)
J. Wang
Epitaxial BiFeO₃ multiferroic thin film heterostructures
Science
(2003)
H. Jeen et al.
Growth and characterization of multiferroic BiMnO₃ thin films
J. Appl. Phys.
(2011)

F. Huang et al.

Effect of Nd dopant on magnetic and electric properties of BiFeO₃ thin films prepared by metal organic deposition method

Appl. Phys. Lett.

(2006)

S.K. Singh et al.

Room temperature ferroelectric properties of Mn-substituted BiFeO₃ thin films deposited on Pt electrodes using chemical solution deposition

Appl. Phys. Lett.

(2006)

S.K. Singh et al.

Microstructure and frequency dependent electrical properties of Mn-substituted BiFeO₃ thin films

J. Appl. Phys.

(2007)

V.R. Palkar et al.

Effect of Mn substitution on magnetoelectric properties of bismuth ferrite system

J. Appl. Phys.

(2003)

E.M. Choi et al.

Strong room temperature magnetism in highly resistive strained thin films of BiFe_0.5Mn_0.5O₃

Appl. Phys. Lett.

(2011)

A.F.M. Santos et al.

Epitaxial growth and properties of metastable BiMnO₃ thin films

Appl. Phys. Lett.

(2004)

F. Yan et al.

Effect of bottom electrodes on nanoscale switching characteristics and piezoelectric response in polycrystalline BiFeO₃ thin films

J. Appl. Phys.

(2011)

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Structural phase transition and enhanced ferroelectricity in Bi(Fe1 − xMnx)O3 thin films deposited by pulsed laser deposition

Highlights

Abstract

Introduction

Section snippets

Experimental procedure

Structural properties

Conclusions

Acknowledgments

J. Phys. Chem. Solids

Appl. Surf. Sci.

J. Solid State Chem.

J. Magn. Magn. Mater.

Mater. Lett.

Multiferroic and magnetoelectric materials

Nature

Multiferroics: progress and prospects in thin films

Nat. Mater.

Physics and applications of bismuth ferrite

Adv. Mater.

Epitaxial BiFeO3 multiferroic thin film heterostructures

Science

Growth and characterization of multiferroic BiMnO3 thin films

J. Appl. Phys.

Effect of Nd dopant on magnetic and electric properties of BiFeO3 thin films prepared by metal organic deposition method

Appl. Phys. Lett.

Room temperature ferroelectric properties of Mn-substituted BiFeO3 thin films deposited on Pt electrodes using chemical solution deposition

Appl. Phys. Lett.

Microstructure and frequency dependent electrical properties of Mn-substituted BiFeO3 thin films

J. Appl. Phys.

Effect of Mn substitution on magnetoelectric properties of bismuth ferrite system

J. Appl. Phys.

Strong room temperature magnetism in highly resistive strained thin films of BiFe0.5Mn0.5O3

Appl. Phys. Lett.

Epitaxial growth and properties of metastable BiMnO3 thin films

Appl. Phys. Lett.

Effect of bottom electrodes on nanoscale switching characteristics and piezoelectric response in polycrystalline BiFeO3 thin films

J. Appl. Phys.

Structural phase transition and enhanced ferroelectricity in Bi(Fe_1 − xMn_x)O₃ thin films deposited by pulsed laser deposition

Epitaxial BiFeO₃ multiferroic thin film heterostructures

Growth and characterization of multiferroic BiMnO₃ thin films

Effect of Nd dopant on magnetic and electric properties of BiFeO₃ thin films prepared by metal organic deposition method

Room temperature ferroelectric properties of Mn-substituted BiFeO₃ thin films deposited on Pt electrodes using chemical solution deposition

Microstructure and frequency dependent electrical properties of Mn-substituted BiFeO₃ thin films

Strong room temperature magnetism in highly resistive strained thin films of BiFe_0.5Mn_0.5O₃

Epitaxial growth and properties of metastable BiMnO₃ thin films

Effect of bottom electrodes on nanoscale switching characteristics and piezoelectric response in polycrystalline BiFeO₃ thin films