Invited Paper MI+SA-WeM10
Intrinsic Interfacial Phenomena and Spin Structure in Nano and Heterostructures
Wednesday, November 1, 2017, 11:00 am, Room 11
One fundamental route towards the control of the electronic properties of materials is via modulation of the charge carrier density, either through chemical, ionic, or electrostatic doping. The latter process relies on charge screening effects at the interface between a gate dielectric and a channel layer, and forms the basis of important technological applications, such as field effect devices. A more recent extension of this concept employs a ferroelectric gate dielectric in combination with correlated materials to form switchable, non-volatile ferroelectric field effect devices, or artificial multiferroic heterostructures relying on interfacial modulations of the magnetic properties of the channel layer [1]. A particularly striking manifestation of the latter has been found in ferroelectric/ferromagnetic mixed valency manganite heterostructures, where control of the ground state of a 10 unit cells La0.8Sr0.2MnO3 film (LSMO) in contact with a ferroelectric PZT layer leads to a spin reconstruction in the LSMO that is intrinsic to the PZT/LSMO interface, as a consequence of the modulation in the charge density [2]. In this contribution I discuss recent results aiming at resolving the magnetic configuration of the interfacial spin reconstruction in the LSMO using soft x-rays as a localised probe of the electronic and magnetic structure at the interface. In particular, I show that resonant x-ray magnetic reflectivity can probe deeply buried interfaces with high sensitivity. Changes in the reflectivity spectra are observed upon switching of the ferroelectric polarisation and reflect directly the changes in the spin structure at the interface. The results of these studies underline the unique strengths of synchrotron x-ray light to address fundamental and practical issues in a wide range of physical systems [3].[1] C A F Vaz, F J Walker, C H Ahn, and S Ismail-B, J. Phys.: Condens. Matter 27 (2015) 123001.
[2] C. A. F. Vaz, J. Hoffman, Y. Segal, J.W. Reiner, R. D. Grober, Z. Zhang, C. H. Ahn, and F. J. Walker, PRL 104, 127202 (2010).
[3] M.-A. Husanu and C.A.F. Vaz, Spectroscopic characterisation of multiferroic interfaces. In C. Cancellieri and V. N. Strocov (editors), Spectroscopy of TMO interfaces. Springer-Verlag, 2017 (forthcoming).