Download or read book Topological and Electronic Properties of Electron doped Manganite Thin Films written by Lorenzo Vistoli and published by . This book was released on 2019 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Oxide thin films feature a wide range of physical phenomena and rich phase diagrams tunable by strain and interface engineering. CaMnO3, in particular, is extremely sensitive to both doping and strain and, when grown with compressive strain, transitions from an insulating and antiferromagnetic state to a metallic and weakly ferromagnetic state at only 2% Ce doping.We used a combination of angle-resolved photoemission spectroscopy, magnetotransport, and density functional theory to study the electronic properties of this material. We observed the existence of two separate charge carriers, light electrons and heavy polarons, whose physical nature differs because of drastically different couplings to phonons. We ascribe these differences to a different relative band filling due to correlations, which enhance greatly the coupling to phonons of the heavy polarons band. Magnetotransport experiments reveal that the polaron band dominates transport despite its lower mobility.Compressive strain also gives rise to a strong magnetic anisotropy which stabilizes magnetic bubbles that accompany a topological Hall effect. This suggests that these bubbles have topological character, i.e. are skyrmion bubbles. The topological Hall effect diverges as the manganite approaches the metal-insulator transition at low dopings. We used a recently developed theory in order to interpret this behavior, and we conclude that correlations may come into play, enhancing the effective mass of the carriers, and in turn the topological Hall effect.As this manganite is highly sensitive to changes in doping and carrier density, we grew BiFeO3/(Ca,Ce)MnO3 ferroelectric field-effect transistors. Upon switching the ferroelectric polarization of the BiFeO3 top layer, we could not observe any sizable changes in the properties of the underlying manganite layers. We used transmission electron microscopy to study the properties of these bilayers with an atomic resolution, and we observed that polarization pinning at the BiFeO3/(Ca,Ce)MnO3 impedes a complete switch of the polarization and so reduces the operational capabilities of these devices. Nevertheless, we could detect modifications of the electronic properties of the manganite induced by polarization reversal at the atomic scale.
Download or read book Epitaxial Thin Films and Heterojunctions of Electron Doped Manganite La1 Xhfxmno3 written by Libin Jin and published by . This book was released on 2017-01-26 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: This dissertation, "Epitaxial Thin Films and Heterojunctions of Electron Doped Manganite La1-xHfxMnO3" by Libin, Jin, 靳立彬, was obtained from The University of Hong Kong (Pokfulam, Hong Kong) and is being sold pursuant to Creative Commons: Attribution 3.0 Hong Kong License. The content of this dissertation has not been altered in any way. We have altered the formatting in order to facilitate the ease of printing and reading of the dissertation. All rights not granted by the above license are retained by the author. Abstract: Abstract of thesis entitled EPITAXIAL THIN FILMS AND HETEROJUNCTIONS OF ELECTRON DOPED MANGANITE La Hf MnO 1-x x 3 Submitted by Jin Libin For the Degree of Master of Philosophy at The University of Hong Kong in October 2015 The strong electron correlated system like perovskite oxides in transition metal oxides have been studied for many years. Most efforts have been focused mainly 3+ 4+ on the hole-doped manganites with Mn /Mn double exchange interaction. Recently, the tetravalent ions doping has attracted considerable attention to make electron doping LaMnO compounds. Such electron-doped manganites may be applied for fabrication of all-manganites devices potentially. The sensitivities to magnetic fields, currents, electric fields, photo illumination and mechanical strain make the electron-doped manganites of great interests for relevant applications. In this thesis, thin films and heterojunctions of tetravalent hafnium doped perovskite manganite La Hf MnO were fabricated. The hafnium shows a 1-x x 3 unique tetravalent state as well as an ion radius closed to trivalent lanthanum ion. These properties make the investigation on La Hf MnO system relatively 1-x x 3 simple and reliable. The structural and physical properties of La Hf MnO (x=0.1, 0.2, 0.3) thin 1-x x 3 films were studied systematically. The crystal structure and epitaxy of La 1- Hf MnO thin films were examined by X-ray diffraction. The temperature x x 3 dependent resistance and magnetization of different samples were investigated in detail. Both temperature dependent resistance and field dependent magnetization indicated the evident transition between paramagnetic and ferromagnetic states. The electronic structures of epitaxial La Hf MnO were measured by X-ray 0.9 0.1 3 Photoelectron Spectroscopy. Both spectrum of Mn 3s and Mn 2p demonstrated 2+ 3+ the composition of Mn /Mn ions. Such evidence strongly suggested the electron-conductive mechanism in La Hf MnO systems. 0.9 0.1 3 The heterojunctions composed of oxygen-deficient SrTiO and 3-δ La Hf MnO thin films have been studied. These heterojunctions demonstrate 0.9 0.1 3 good rectifying characteristics with very low leakage current and high breakdown voltage in a wide temperature range. X-ray diffraction and electron backscattering diffraction measurements reveal that both SrTiO and La Hf MnO layers 3-δ 0.9 0.1 3 have single crystal nature and [001]-orientation. Transmission electron microscope images show an excellent epitaxial growth of SrTiO and 3-δ La Hf MnO layers. Such all-oxides junctions utilizing the bi-layer 0.9 0.1 3 heterostructure may be applied in microelectronic devices. The n-i-p heterojunctions have been fabricated by depositing an n-type La Hf MnO layer on p-type Si with a thin SrTiO intermediate layer. These 0.9 0.1 3 3 junctions exhibit excellent rectifying properties for temperature from 20 K to 300 K. Under illumination of 630 nm light a remarkable photocurrent has been observed. The photosensitivity is over 1200% under -3 V bias and illumination of the light at room temperature, demonstrating very a pronounced photocurrent effect. The injection of photo-carriers could be responsible for the observed phenomenon. The obtained results in this thesis demonstrate the electron-conductive mechanism in La Hf MnO system. The La Hf MnO based heterojunctions 1-x x 3 0.9 0.1 3 show remarkable characteristics and may
Download or read book Growth electronic structure and properties of electron doped EuO thin films written by Simone Altendorf and published by . This book was released on 2011 with total page 145 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Structural Magnetic and Electronic Properties of 110 OrientedEpitaxial Thin Films of Bilayer Manganite La1 2Sr1 8Mn2O7 written by and published by . This book was released on 2005 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: We have synthesized (110)-oriented epitaxial thin films of the bilayer (n=2) manganite, La{sub 1.2}Sr{sub 1.8}Mn2O--, with the metallic/ferromagnetic a-b planes lying perpendicular to the substrate surface and the c-axis aligned in the plane of the film. X-ray diffraction and transmission electron microscopy confirm the alignment of the a-b planes along the [1{bar 1}0] substrate direction. The films consist primarily of the n=2 phase with a minor component of the n=1 (La, Sr)2MnO4 and n=(infinity) (La, Sr)MnO3 phases. A resistivity maximum coincides with a ferromagnet/paramagnet transition at a reduced T{sub c}(almost equal to)90K (vs. 120K for bulk), indicative of the effects of epitaxial strain. The films display similar anisotropic properties to their bulk counterpart with the magnetically easy direction confined to the a-b planes and 20-200 times lower resistivity for current flowing along the a-b planes compared to the c-axis.
Download or read book Growth Electric Structure and Properties of Electron doped EuO Thin Films written by Simone Altendorf and published by . This book was released on 2011 with total page 145 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Correlation Between Structural and Electronic Properties of Co Evaporated Doped Organic Thin Films written by Daniela Donhauser and published by . This book was released on 2014-10-23 with total page 150 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Epitaxial Thin Films and Heterojunctions of Electron Doped Manganite La1 xHfxMnO3 written by 靳立彬 and published by . This book was released on 2015 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Thin Films and Heterostructures for Oxide Electronics written by Satishchandra B. Ogale and published by Springer Science & Business Media. This book was released on 2005-11-21 with total page 416 pages. Available in PDF, EPUB and Kindle. Book excerpt: Oxides form a broad subject area of research and technology development which encompasses different disciplines such as materials science, solid state chemistry, physics etc. The aim of this book is to demonstrate the interplay of these fields and to provide an introduction to the techniques and methodologies involving film growth, characterization and device processing. The literature in this field is thus fairly scattered in different research journals covering one or the other aspect of the specific activity. This situation calls for a book that will consolidate this information and thus enable a beginner as well as an expert to get an overall perspective of the field, its foundations, and its projected progress.
Download or read book Magnetic and Electrical Properties of Transition metal doped Oxide Thin Films written by Ching-yee Lam and published by . This book was released on 2009 with total page 552 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Journal of the Physical Society of Japan written by and published by . This book was released on 2005 with total page 424 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Structure and Electronic Properties of Pure and Nitrogen Doped Nanocrystalline Tungsten Oxide Thin Films written by Venkata Rama Sesha Ravi Kumar Vemuri and published by . This book was released on 2013 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Infrared Spectroscopy of Complex Oxides of Phase Separated Manganites and Electron doped Cuprates written by Naveen Margankunte and published by . This book was released on 2008 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: ABSTRACT: Our study examined the infrared optical properties of complex oxides of phase separated manganite thin films and electron-doped cuprates as a function of temperature and magnetic field covering a range of doping on various substrates. The principal conclusion of this study for manganites is that low energy optical properties are sensitive to phase separation in manganites. The optical constants indicate a percolative type of insulator-metal transition and effective electron density analyzes indicate that with large cation disorder, the description of the optical conductivity is not amenable to mean field models of double exchange and Jahn-Teller distortions. The magneto-optic study of electron-doped cuprates indicate that the optical properties are unaffected by the application of magnetic fields of 31T.
Download or read book Effects of Dopant Molecules on the Electronic Properties of Organic Thin Films written by Joel Walter Pankow and published by . This book was released on 1991 with total page 292 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Systematic Studies of the Effect of Pressure on Magnetic and Electronic Properties of La2 3Ca1 3MnO3 Thin Films with Various Thicknesses written by Sarkis Y. Jacob and published by . This book was released on 1999 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Interest in mixed-valent perovskite manganese oxides of La\-xAxMnO^ (v4-divalent alkaline earth Ca, Sr or Ba), whose unusual properties were discovered nearly a half century ago, has recently been revived. The discovery of the colossal magnetoresistance and pressure effects introduced new questions concerning the complex interplay between lattice structure, magnetism and transport in doped perovskite manganites. In this study, we report our experimental investigations of pressure and magnetic field dependencies of La-i/sCai/sMnOs (LCMO) epitaxial films with various thickness on SrTiO$ substrate. An analysis of film thickness dependency of the resistivity of LCMO epitaxial films under pressure and magnetic field has been performed by taking into account substrate contributions. This verifies the correlation of lattice distortion with magnetic and transport properties. Strong dependencies of Mn - O - Mn bond bending and Mn - O bond stretching with pressure as well as Mn spin alignment with magnetic field, and the lattice distortion induced by the substrate are discussed.
Download or read book Magnetic and Electronic Properties of Weyl Semimetal Co2MnGa Thin Films written by Peter Swekis and published by . This book was released on 2021 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Electronic properties of organic molecular thin films in condensed and interfacial states with metal substrates written by Ying Zou and published by . This book was released on 2004 with total page 160 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Spatially Resolved Studies Of Electronic Phase Separation And Microstructure Effects In Hole Dopped Manganites written by and published by . This book was released on 2003 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The main focus of this thesis is in understanding the role of phase separation and microstructure in determining the physical properties of manganites. We also aim to be able to tune certain material properties using appropriate control mechanisms. For this, an understanding of the local electronic properties of manganites is essential. We thus set out to study the local electronic states in manganites using a highly sensitive probe: the scanning tunneling microscope (STM). The chapter 1 of the thesis gives an introduction to manganites, and of how manganites are susceptible to various perturbations due to closely lying ground states and an intricate interplay of their charge, spin and lattice degrees of freedom. Chapter 2 of this thesis gives a detailed account of various experimental methods used in the current investigation. In particular, we describe the design and fabrication of a variable temperature ultra-high vacuum scanning tunneling microscope (UHV-STM) which was used to carry out spatially resolved measurements on various manganite systems. This chapter also describes sample fabrication techniques by which strain and microstructure of thin films can be controlled. Other characterization techiniques, such as tranport and magnetotransport measurements, are also described in detail. Chapter 3 presents our investigation of the role of microstructure and phase separation on the DOS and local electronic properties of manganite thin films. We describe various spatially resolved STM/STS measurements carried out on La0.67Sr0.33MnO3 and La0.67Ca0.33MnO3 films having different micrsotructure and varying degrees of phase separation. We also present a theoretical model used in interpreting STS data to account for finite temperature effects and explain the existing data in this context. We use this model to gain insight into the behaviour of the DOS at EF near the MIT where thermal smearing can often give rise to misleading inferences. Chapter 4 presents our investigat.
