Bulletin of the American Physical Society
APS March Meeting 2020
Volume 65, Number 1
Monday–Friday, March 2–6, 2020; Denver, Colorado
Session B52: Complex Oxide Films, Surfaces, and Interfaces I |
Hide Abstracts |
Sponsoring Units: DCMP Chair: Matthew Brahlek, Oak Ridge National Lab Room: Mile High Ballroom 1E |
Monday, March 2, 2020 11:15AM - 11:27AM |
B52.00001: Growth of the Transparent Correlated Metal SrVO3 Lishai Shoham, Maria Baskin, Myung-Geun Han, Yimei Zhu, Lior Kornblum <div style="direction: ltr;">The ongoing search for earth-abundant transparent conduction oxides (TCOs) has spread across a wide variety of research fields, highlighting the correlated metal SrVO3 as a potential candidate. SrVO3 displays high conductivity and transparency in the visible. Moreover, SrVO3 is an attractive candidate for future electronics. A major hurdle for the synthesis of high quality SrVO3 is to mitigate the formation of defects throughout the thin film. These defects can cause electron scattering and result in high resistivity and obscure some of the interesting physics. Film growth was done with molecular beam epitaxy (MBE), providing a scalable and industry-compatible fabrication process. In this work we present low defect SrVO3 films with residual resistivity ratios exceeding 10 and room temperature resistivities in the order of 30 µΩ cm. Careful analysis of the structural and electronic properties of the SrVO3 films paves the way towards further improvement of their quality and their implementation as TCO in optoelectronics and renewable energy devices. |
Monday, March 2, 2020 11:27AM - 11:39AM |
B52.00002: Magnetic properties in strained PrVO3 thin films Wilfrid Prellier Transition metal oxides often having a perovskite structure form a wide and technologically important class of compounds. In these systems, ferroelectric, ferromagnetic, ferroelastic, or even orbital and charge orderings can develop and eventually coexist. These orderings can be tuned by external electric, magnetic, or stress field, and the cross-couplings between them enable important multifunctional properties, such as piezoelectricity, magneto-electricity, or magneto-elasticity. |
Monday, March 2, 2020 11:39AM - 11:51AM |
B52.00003: Phase transformation by superoxygenation in cuprate and iridate thin films Chao C Zhang, Hao Zhang, Nicolas Gauquelin, Shaobo Cheng, Gianluigi Botton, Christopher McMahon, David Geoffrey Hawthorn, Patrick Clancy, Saehwan Chun, Ambrose Seo, Young-June Kim, John Y.T. Wei High-pressure O2 has previously been used to hole-dope and stabilize high-oxidation phases of cuprates. We extend this superoxygenation technique to materials in thin film form since they are more reactive due to their large surface-to-volume ratio. YBa2Cu3O7-δ (YBCO) thin films grown by PLD are annealed in up to 700 atm O2 and then characterized by TEM, XRD and XAS. The annealed films show phase conversion to Y2Ba4Cu7O15-δ and Y2Ba4Cu8O16, as well as regions well as regions of YBa2Cu5O9-δ and YBa2Cu6O10-δ. Epitaxial thin films of Sr2IrO4 are subjected to extended high-pressure annealing and similarly characterized. The post-annealed films show up to 3 order-of-magnitude drop in room temperature resistivity and an evolution towards semi-metallic behaviour. Furthermore, as film thickness is reduced, the annealed films show a structural transformation towards a quasi-cubic phase. Our results demonstrate the potential of using superoxygenation to stabilize exotic phases of transition metal oxides not achievable in bulk form and to create novel materials by selectively transforming constituent layers in multilayer films. [1] |
Monday, March 2, 2020 11:51AM - 12:03PM |
B52.00004: Coupling lattice instabilities across the interface in ultrathin oxide heterostructures Thierry van Thiel, Jennifer Fowlie, Carmine Autieri, Nicola Manca, Makars Siskins, Dmytro Afanasiev, Stefano Gariglio, Andrea Caviglia The resistivity of ultrathin SrIrO3 films grown epitaxially on SrTiO3 displays an anomaly at the temperature corresponding to the cubic tetragonal transition of the substrate. We investigate its origin through synchrotron X-ray diffraction measurements, electronic transport and ab-initio calculations. The effect is ascribed to a redistribution of orthorhombic structural domains, driven by the cubic-tetragonal transition of SrTiO3. The compressive strain induced by the substrate is found to force the in-phase octahedral rotation axis of the film to lie in-plane, giving rise to a twofold degenerate domain structure that couples to SrTiO3 tetragonal domains. Transport measurements in van der Pauw devices reveal that a strong anisotropy of the longitudinal resistivity develops below the transition temperature. The strong structure-property relationships in the iridates makes these compounds particularly suitable for static and dynamic coupling at interfaces, providing a promising route towards realizing novel functionalities in oxide heterostructures. |
Monday, March 2, 2020 12:03PM - 12:15PM |
B52.00005: Structure of SrRuO3 films on SrTiO3 (001) in the ultrathin limit Prahald Siwakoti, Mohammad Saghayezhian, Zhen Wang, Yimei Zhu, E Ward Plummer, Jiandi Zhang The observation of unconventional anomalous Hall effect in SrRuO3 films on SrTiO3 has been suggested as the signature for the existence of topologically non-trivial magnetic structures driven by Dzyaloshinskii – Moriya (DM) interaction [1,2]. However, experimental evidence for RuO6 distortion, which should be directly correlated with DM interaction, is far from clear. We have carried out a study on the evolution of lattice structure and its relation to the magneto-transport properties of SrRuO3 films with thickness in the ultra-thin limit (< 10 unit-cells) utilizing in-situ Low Energy Electron Diffraction, ex-situ High Resolution Scanning Transmission Electron Microscopy and transport measurements. We discuss the lattice distortion effect on the Dzyaloshinskii – Moriya interaction in the system. |
Monday, March 2, 2020 12:15PM - 12:27PM |
B52.00006: Electronic and lattice coupling in thin films of Nd1-xLaxNiO3 Jennifer Fowlie, Bernat Mundet, Alexandru Bogdan Georgescu, Claribel Dominguez Ordonez, Marta Gibert, Jean-Marc Triscone The solid solution Nd1-xLaxNiO3 spans a range of materials properties. From NdNiO3 (x = 0), a low temperature antiferromagnetic insulator with monoclinic symmetry to LaNiO3 (x = 1) a metallic paramagnet with rhombohedral symmetry [1]. Using an intermittant sputtering technique, we grow high quality epitaxial thin films of this solid solution on various substrates and, in this way, achieve an analog control of the composition. We report here of an unexpected discontinuous electronic behaviour - an abrupt change from an insulating to a metallic groundstate - and establish a connection to the symmetries of the system. Our work sheds light on a little-explored area of the rare earth nickelate phase diagram. |
Monday, March 2, 2020 12:27PM - 12:39PM |
B52.00007: Co valence transformation in isopolar LaCoO3 / LaTiO3 perovskite heterostructures via interfacial engineering Georgios Araizi-Kanoutas, Jaap Geessinck, Nicolas Gauquelin, Steef Smit, Xanthe Verbeek, Shrawan Mishra, Peter Bencok, Christoph Schlueter, Tien-Lin Lee, Dileep Krishnan, Jo Verbeeck, Guus Rijnders, Gertjan Koster, Mark Golden Charge transfer up to a single electron per interfacial unit cell across the non-polar heterointerface consisting of the Mott insulator LaTiO3 and the charge-transfer insulator LaCoO3 was studied in multi-layered films grown by PLD, using element-specific soft X-ray absorption, magnetic dichroism, TEM and hard X-ray photoemission spectroscopies. |
Monday, March 2, 2020 12:39PM - 12:51PM |
B52.00008: Long-range ordered domain walls in MBE-grown BiFeO3 thin films and manipulation of their electrical properties Yongjian Tang, Antonio B Mei, Jürgen Schubert, Sahar Saremi, Ludi Miao, Lane Wyatt Martin, Darrell Schlom, Daniel Ralph Multiferroic BiFeO3 thin films can allow electrical control of magnetism at room temperature and potentially magnetic control of electric polarization. We have investigated the use of adsorption-controlled molecular-beam epitaxy to grow BiFeO3 thin films, as an alternative to the more commonly-used pulsed laser deposition or sputtering. We demonstrate unprecedentedly long-range domain periodicity of domain walls in commensurately strained BiFeO3/SrRuO3/DyScO3(110)o epitaxial heterostructures. We observe two domain variants under piezoresponse force microscopy (PFM), which form alternating 140-nm-wide striped domains. Conductive AFM shows that the domain walls exhibit enhanced conductivity relative to the bulk and electrical rectification. For applications, ion irradiation can be used to reduce the through-film leakage without increasing the coercive field for ferroelectric switching. Doping with lanthanum is effective in reducing the strength of ferroelectric polarization, a necessary step to enable magnetic control of the polarization. |
Monday, March 2, 2020 12:51PM - 1:03PM |
B52.00009: Properties of the BiVO4 (010) surface in single crystals and epitaxially grown samples: A joint first-principles and experimental effort Wennie Wang, Patrick Strohbeen, Dongho Lee, Chenyu Zhou, Jason Kawasaki, Kyoung-Shin Choi, Mingzhao Liu, Giulia Galli As a prototypical oxide for water photocatalysis, BiVO4 has many advantageous optoelectronic properties, including strong absorption in the visible and a favorable band alignment with water. However, its use as a photo-absorber is limited by its inefficient charge dynamics, especially at interfaces. Here, we present an integrated experimental and computational study aimed at an atomistic understanding of the surface morphology and electronic properties of BiVO4 as a function of oxygen vacancy concentration. |
Monday, March 2, 2020 1:03PM - 1:15PM |
B52.00010: Multi-level ionic conductivity in Ca-doped BiFeO3 thin films Jeonghun Suh, Ji Soo Lim, Heung-Sik Park, Chan-Ho Yang Ca-doped bismuth ferrite is a promising material for studying collective ionic migration in solids [1]. We conduct impedance analysis with different magnitudes of AC voltage to understand the ionic conduction mechanism of this material. To suppress the electronic contribution to the conductivity, we annealed the sample in a reducing condition at elevated temperatures before the measurement. By using the mixed conductor equivalent circuit model [2], we obtain ionic conductivity, which shows a multi-level feature. This result shows consistency with the observation from electroforming experiments with DC voltages. This work provides useful insight into the ionic conduction mechanism in solids. |
Monday, March 2, 2020 1:15PM - 1:27PM |
B52.00011: Observation of anisotropic filamentary conduction pathways in Ca-doped bismuth ferrite thin films Heung-Sik Park, Ji Soo Lim, Jeonghun Suh, Chan-Ho Yang Ionic migration is a key ingredient for applications such as oxide electrolytes and resistive switching memories. We investigate the evolution of the ionic conduction pathways based on optical contrast in an epitaxial Bi0.7Ca0.3FeO3-δ thin film where oxygen vacancies are spontaneously produced.[1] We visualized electroforming processes in the hundreds-micron-scale material channels between coplanar electrodes with a constant electric bias at an elevated temperatures, systemically varying the channel orientation with respect to the crystal axis.[2] At the initial stage of electroforming, conducting filaments are created and propagate nearly along the crystal axes <100>, thereby making orthogonal self-similar networks. We also find that the filament-type ionic conduction is abruptly transformed to the bulk conduction around the time when the filament pathways connect both electrodes. These results offers useful insight into collective ionic migration in crystalline solids. |
Monday, March 2, 2020 1:27PM - 1:39PM |
B52.00012: Charge transport and distribution at the interfaces of SrTiO3/LaAlO3/SrTiO3 (100) (STO/LAO/STO (100)) Akhilesh Kumar Singh, C.P. Su, T.C. Wu, M.C. Chen, M.Y. Song, Y.C. Lai, Guang-Yu Guo, M.-W Chu, Wei-Li Lee The existence of a quasi-2-dimensional hole gas (q2DHG) in STO/LAO/STO (100) has been revealed by several groups. In this report, the STO(6-uc)/LAO(t-uc)/STO (100) samples with t = 5 and 3 were grown using oxide MBE technique. From magneto-transport measurements at low temperatures and difference gate voltages (Vg), a clear signature for the existence of q2DHG was uncovered from rigorous two band model fittings to magneto-conductance data. At T = 2K and Vg = + 100V, the sheet density for q2DHG is as large as 1.47 x 1013 per cm2. Intriguingly, both the sheet densities for q2DEG and q2DHG increase with increasing positive Vg, which supports for a spatially separated electron-hole bilayer at the interfaces [1]. On the other hand, STEM-EELS measurements with atomic scale resolution across the interfaces were performed. The suppressed q2DHG in STO/LAO/STO (100) in the ultra-thin LAO limit can be attributed to the depolarization field within the LAO layer, arising from the strain-field interference across the two closely-spaced interfaces [2]. In principle, q2DHG can emerge by compensating the depolarization field, which is achievable either by increasing the LAO thickness or by electrical gating. [1] Singh et al., PRM 2, 114009 (2018). [2] Su et al., PRM 3, 075003 (2019). |
Monday, March 2, 2020 1:39PM - 1:51PM |
B52.00013: Observation of polar domains in a relaxor La-substituted BiFeO3 thin film Youngki YEO, Yong-Jin Kim, Mujin You, Chan-Ho Yang Relaxor ferroelectrics have been widely studied because of their unique physical properties including high permittivity, high piezoelectric effects, etc. The existence of polar nanoregions (PNRs) is believed to be responsible for relaxor behaviors [1]. However, there is a lack of studies on PNRs linked to the flexoelectric effect. In this work, we report the direct observation of PNRs within tetragonal BiFeO3 near morphotropic phase boundaries (MPBs) which are expected to involve large strain gradient. Heavily La-substituted BiFeO3 thin films (BLFO) grown on LaAlO3 (001) have been employed to explore the PNRs with the aid of an angle-resolved lateral piezoresponse force microscopy [2]. BLFO has been thought to be isotropic monoclinic energies [3]. the flexoelectric effect on tetragonal BLFO near MPBs stabilizes various monoclinic phases. The frequency-dependent dielectric anomalies and diffuse x-ray scattering have been confirmed to identify that our system shows the typical relaxor behaviors. Our findings will offer valuable information to study the role of the flexoelectric effect on the formation of PNRs. |
Monday, March 2, 2020 1:51PM - 2:03PM |
B52.00014: The linear electro-optical effect in thin oxide films Alexander Demkov, Ali Hamze, Wente Li, Therese Paoletta, Kurt D Fredrickson The linear electro-optical (EO) effect, also known as the Pockels effect, has been the subject of increasing interest due to its potential for use in silicon photonic applications. As such, it is necessary to find materials that have a strong EO response in thin film form, which is essential for low power and small footprint devices. In this talk we will discuss general design rules for developing strong Pockels materials inferred from first principles theory. We will discuss the Pockels effect in BaTiO3, strained SrTiO3, LiB3O5 (LBO) and CsB3O5 (CBO) and use these materials as prototypical examples of where conventional wisdom breaks down. We analyze how the EO response is related to the optical phonon frequencies, Raman susceptibility and mode polarization and elucidate the underlying physical phenomena behind the large Pockels effect. |
Follow Us |
Engage
Become an APS Member |
My APS
Renew Membership |
Information for |
About APSThe American Physical Society (APS) is a non-profit membership organization working to advance the knowledge of physics. |
© 2024 American Physical Society
| All rights reserved | Terms of Use
| Contact Us
Headquarters
1 Physics Ellipse, College Park, MD 20740-3844
(301) 209-3200
Editorial Office
100 Motor Pkwy, Suite 110, Hauppauge, NY 11788
(631) 591-4000
Office of Public Affairs
529 14th St NW, Suite 1050, Washington, D.C. 20045-2001
(202) 662-8700