APS March Meeting 2012
Volume 57, Number 1
Monday–Friday, February 27–March 2 2012;
Boston, Massachusetts
Session D2: Invited Session: Harnessing Local Atomic Structure to Control Magnetic Interactions in Complex Oxides
2:30 PM–5:30 PM,
Monday, February 27, 2012
Room: 204AB
Sponsoring
Unit:
GMAG
Chair: Steven May, Drexel University
Abstract ID: BAPS.2012.MAR.D2.5
Abstract: D2.00005 : Directly probing the effect of strain on magnetic exchange interactions
4:54 PM–5:30 PM
Preview Abstract
Abstract
Author:
Kathrin Dorr
(Institute for Physics, MLU Halle-Wittenberg)
Thin films of transition metal oxides of the perovskite type ABO$_{3}$ (B =
3d or 4d metal) have revealed abundant examples for strain-driven changes of
magnetic ordering. One most popular is the strain-induced ferromagnetic
ferroelectric state of otherwise antiferromagnetic paraelectric EuTiO$_{3}$.
Another promising example is the strain control of orbital occupation and
magnetic coupling at oxide interfaces of SrRuO$_{3}$ with manganites. In
spite of strong efforts, the theoretical treatment of magnetic exchange in
complex oxides has remained a challenge, and experiments continue to show
unpredicted / unexplained large effects of the epitaxial strains in films.
In order to provide meaningful experimental data on strain dependences,
epitaxial thin films should be grown in various coherent strain states on
different substrates without changing anything but the strain. This is
inherently difficult: possible problems may arise from a strain-dependent
oxidation level or microstructure. As a complementary approach, the in-plane
strain of epitaxial oxide films can be controlled reversibly using a
piezoelectric substrate, even though the accessible reversible strain of 0.1
-- 0.2{\%} is an order of magnitude smaller. In my talk, I will address
reversible-strain studies on La$_{0.7}$Sr$_{0.3}$MnO$_{3}$,
La$_{1-x}$Sr$_{x}$CoO$_{3}$ (x = 0, 0.2, 0.3) und SrRuO$_{3}$ films, showing
the strain response of the magnetic Curie temperature, the magnetization and
the electrical resistance and discussing the current understanding of the
strain effects on magnetic ordering. In La$_{0.8}$Sr$_{0.2}$CoO$_{3}$, a
strain-driven phase transition between ferromagnetic and spin-glass-like
could be established by combining the piezoelectric substrate with a tuned
buffer system providing varied as-grown strain states. In SrRuO$_{3}$, a
tetragonal tensile strain state shows a suppression of the ordered magnetic
moment. Lattice parameters and symmetries of the films were determined by
x-ray diffraction. It is noted that the atomic displacements (bond lengths
and angles) under strain in these compounds are yet essentially unknown and
subject to present research.
To cite this abstract, use the following reference: http://meetings.aps.org/link/BAPS.2012.MAR.D2.5