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Topic Code: Magnetoelectric effects in the artificial LSMO/PZT multiferroics. Robert Kruk, Philipp M. Leufke, Christian Reitz, Horst Hahn Institute of Nanotechnology (INT), Karlsruhe Institute of Technology (KIT) Hermann-von-Helmholtz Platz 1, 76344 Eggenstein-Leopoldshafen, Karlsruhe, Germany [email protected] Abstract: In this work the results of studies on the magnetoelectric coupling in the artificial multiferroic La1−xSrxMnO3/Pb(Zr,Ti)O3 (LSMO/PZT) heterostructures are presented. This multiferroic was – for the first time – in-situ investigated in a superconductive quantum interference device (SQUID). 1. INTRODUCTION The concept of electronically tuneable properties extends the field-effect principle (very well-known in field-effect transistors) and reversible electrochemistry to control a broad spectrum of physical properties in material systems. It has been proposed that generation of the surface charge upon the application of an electric field can lead to significant changes in the material properties, even of highly conducting systems, by judiciously exploiting the high surface-to-volume ratios that are typical of nanostructures [1]. Particularly, a dynamic and reversible control of magnetic properties via applied electrostatic field (surface charge) may be relevant to application areas concerned with the manipulation, storage, and transfer of information by means of electron spins. Indeed, it has been reported for various nanostructures and numerous ferro- and ferrimagnetic materials that an applied surface charge can effectively affect exchange interactions or magnetic anisotropy. effect dominated magnetoelectric coupling mechanism, confirming the concept of electrostatic hole doping of LSMO. For a small surface charge concentration at low temperature, a remarkably large tuning coefficient of about 4 μB/hole was determined suggesting the inducement of a ferromagnetic to antiferromagnetic phase transition in LSMO. Simultaneously, a shift in the magnetic transition temperature at higher surface charge concentration indicates coexistence of the ferromagnetic and antiferromagnetic phases at the LSMO/PZT interface. The dynamic magnetization modulation, resulting upon charging, is interpreted and discussed in the context of the existing magneto-electronic phase diagrams. FIGURES 2. GENERAL TOPIC This presentation provides background and discusses key issues in practical realization of electrically tuneable systems. Selected examples of successful applications of the, surface-charge driven, tuneability principle are presented, including reversible control of magnetic states in strongly correlated oxides and spinels. A notion of reversible electrostatic doping (ED) and its relevance to the dynamic control of magnetic properties will be discussed. Further, this reversible control concept is expanded, by means of polymer-based electrolytes, beyond the thin film geometry to the entire class of nanoporous and nanoparticulate structures. 3. CASE STUDY The response of the magnetization to the electric switching of the PZT ferroelectric film evidences a purely electrostatic coupling mechanism with negligible piezoelectric influence (Fig.1). Temperature dependence of the magnetic modulation upon the ferroelectric stimulation indicates a field- Fig.1. Magnetization response, Δm, of the strongly correlated ferromagnetic La1−xSrxMnO3 to the electric polarization, P, of the PZT ferroelectric. REFERENCES [1]. H. Gleiter, Scripta Mater. 44 (2000) 1161