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Strain-tuned ferroic functionality in CuO at elevated temperatures

English title Strain-tuned ferroic functionality in CuO at elevated temperatures
Applicant Schneider Christof
Number 152913
Funding scheme Project funding (Div. I-III)
Research institution Paul Scherrer Institut
Institution of higher education Paul Scherrer Institute - PSI
Main discipline Condensed Matter Physics
Start/End 01.01.2015 - 31.12.2016
Approved amount 128'005.00
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Keywords (5)

Thin films; magneto-electric coupling; Multiferroics; Second Harmonic Generation; Strain

Lay Summary (German)

Lead
Das Wachstum multiferroischer, epitaktischer Schichten ist eine jüngere Entwicklung. Daher ist die Anzahl der Materialen, die bisher als Filme hergestellt und untersucht wurden, überschaubar. Die multiferroischen Eigenschaften von CuO wurden bisher noch nicht an dünnen Filmen untersucht, obwohl CuO eine der höchsten multiferroischen Übergangstemperaturen aufweist (230K), die möglicherweise weiter erhöht werden kann unter Anwendung von äußerem Druck. CuO hat eine triklinische Struktur und wird mittels gepulster Laserablation als dünne Schicht auf verschiedenen, einkristallinen Unterlagen abgeschieden um möglichst gute kristalline Eigenschaften des Filmes zu erzielen. Diese Schichten werden anschliessend mit Hilfe von nichtlinearen optischen Techniken und Neutronenstreumethoden untersucht um deren multiferroischen und magneto-elektrischen Eigenschaften zu charakterisieren.
Lay summary

Bei den Versuch die Effizienz von elektronischen Bauteilen zu verbessern sowie deren Energieverbrauch zu minimieren, sind Materialien die magnetische und ferroelektrische Eigenschaften vereinen, verstärkt in den Fokus der Forschung getreten. Die Koexistenz von mindestens zwei solcher ferroischer Eigenschaften und deren Kopplung hat das Potential z.B. die magnetischen Eigenschaften eines Bauelementes mit Hilfe eines stromlosen Spannungspulses zu kontrollieren. Multiferroische Materialien bei denen Ferroelektrizität mittels magnetischer Ordnung induziert wird wie z.B. in CuO sind besonders von Interesse für Anwendungen aufgrund ihrer sehr ausgeprägten magneto-elektrischen Kopplung.

Das Projekt wird das Wachstum, Wachstumsmechanismen und den wachstumsinduzierten Stress während der Herstellung von CuO auf verschiedenen Substraten untersuchen. Wir erwarten, dass diese breitangelegte Studie zu Filmen und Multilagen hoher kristalliner Qualität mit multiferroischen Eigenschaften führen wird um magneto-elektrischen Eigenschaften bzw. deren kontrollierte Beeinflussung zu erforschen. Diese Kopplungen sollen u.a. mittels temperaturabhängiger nichtlinearer Optik, Rastersondenmikroskopie (ETHZ) und Neutronenstreumethoden (PSI) untersucht werden.

Direct link to Lay Summary Last update: 29.01.2015

Responsible applicant and co-applicants

Employees

Collaboration

Group / person Country
Types of collaboration
Dr. Max Döbeli Switzerland (Europe)
- in-depth/constructive exchanges on approaches, methods or results
- Publication
- Research Infrastructure

Associated projects

Number Title Start Funding scheme
147049 Structural and magneto-electric properties of strained REMnO3 films 01.11.2013 Project funding (Div. I-III)
169393 Coexisting multiple orders in oxide thin films 01.11.2017 Project funding (Div. I-III)

Abstract

In the attempt to increase efficiency and minimize energy consumption of electronics devices, multiferroics, i.e., compounds unifying magnetic and ferroelectric order in one phase, moved into focus about a decade ago . The coexistence of the two forms of order bear a potential for an unusually strong magnetoelectric coupling which may, e.g., become the basis for controlling magnetization by fast energy-efficient electric voltage pulses instead of electrical currents. Multiferroics in which the ferroelectric order is directly induced by the magnetic order are most promising because of their particularly pronounced magnetoelectric coupling.Attempts are now being made to grow such magnetically induced ferroelectrics as epitaxial films since this offers a variety of advantages. First, films can be implemented into heterostructures to exploit the multiferroic order for the magnetoelectric manipulation of the adjacent constituents. Second, the dimensional confinement and the substrate-induced strain exerted to the film can alter the multiferroic state. For example, antiferromagnetism can be supplemented or replaced by a magnetization or multiferoicity can be induced in the first place. Third, the investigation and control of domains and domain walls becomes simpler because the 3D network of domain walls is replaced by a 2D distribution. The growth of multiferroic epitaxial films is a relatively recent development. As a consequence, not too many different compounds have been studied so far. The multiferroic CuO has not been investigated yet as thin film although CuO has one of the highest multiferroic transition temperatures (230 K) which is predicted to increase further under pressure or strain. The goal of the proposed project is therefore the growth of high-quality multiferroic CuO films and heterostructures using PLD in the Materials Group at PSI and the investigation of the multiferroic properties and magnetoelectric performance of the films using the advanced characterization techniques at the Multifunctional Ferroics Group at ETH. Recursive iteration of the experiments done at PSI and ETH will allow us to advance from the reproducible growth of bulk-like multiferroic CuO films towards CuO films and heterostructures with improved functionality. Here, strain will be the major degree of freedom to achieve this. At the PSI, we will focus at first on the growth, growth mechanisms and growth-induced strain during the deposition of CuO on different substrates. This wide-ranging approach is expected to lead to high quality (structural and multiferroic) thin films. Structural and magnetic studies will also be conducted including neutron diffraction experiments to investigate in detail e.g. the magnetic ground state of the multiferroic thin films. A thorough understanding of the ground state properties affected by strain is necessary to understand the tuning of the magneto-electric properties. At ETH we will characterize the CuO films by temperature-dependent nonlinear optics and force microscopy. Nonlinear optics is a highly symmetry-sensitive optical technique allowing us to analyze the coexisting magnetic and ferroelectric order, including observation of the coupling of magnetic and ferroelectric domains and their magnetoelectric manipulation in applied fields. With a force microscope operated in a variety of modes we will focus on the characterization of the multiferroic domain walls. We will apply our advanced (i.e. non-standard) characterization to samples of increasing quality and complexity: CuO films emulating the bulk properties as closely as possible; CuO films whose properties deviate in a controlled way from the bulk; strained CuO films as ingredient of a multilayer heterostructure where its magnetoelectric properties will be put to use. With their collaboration, the Materials Group and Laboratory for Neutron Scattering at PSI and the Multifunctional Ferroics Group at ETH combine their world-leading expertise in PLD growth, magnetic and advanced nonlinear-optical characterization of functional oxides, a combination that has not been attempted before in such close cooperation. With this synergy we expect significant advances by our project in the field of multiferroics, both towards practical application and a deeper understanding of coupling mechanisms leading to multiferroicity in general.
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