AVS 51st International Symposium
    Semiconductors Monday Sessions
       Session SC+MI-MoM

Paper SC+MI-MoM9
Ferroelectric Field Effect on Ferromagnetism in Diluted Magnetic Insulator Anatase Co:TiO@sub2@

Monday, November 15, 2004, 11:00 am, Room 304B

Session: Dilute Magnetic and Ferromagnetic Semiconductors
Presenter: T. Zhao, University of Maryland
Authors: T. Zhao, University of Maryland
S.R. Shinde, University of Maryland
S.B. Ogale, University of Maryland
H. Zheng, University of Maryland
T. Venkatesan, University of Maryland
R. Ramesh, University of California, Berkeley
S. Das Sarma, University of Maryland
J. Misewich, Brookhaven National Laboratory
Correspondent: Click to Email
Recently considerable success is reported in making a non-magnetic semiconductor ferromagnetic by dilute doping of magnetic impurities. However, the possibilities of extrinsic effects such as dopant clustering, impurity magnetic phases etc., have not been completely ruled out in many systems. In this work we report the first successful implementation of an external electric field modulation of ferromagnetism in an oxide-based DMS anatase Co:TiO@sub2@. An anatase TiO2 layer with 7% Co doping and a ferroelectric PbZr@sub0.2@Ti@sub0.8@O@sub3@ layer were epitaxially grown on a conducting SrRuO@sub3@ buffered LaAlO@sub3@ substrate by pulsed laser deposition. The high-quality of epitaxy and uniform distribution of Co were confirmed by X-Ray diffraction and transmission electron microcopy. The Co:TiO@sub2@ channel grown in this case at a high temperature of 875°C is insulating in nature. The magnetic hysteresis loops of the Co:TiO@sub2@ were measured by superconducting quantum interference device after positive or negative electric poling on PZT. The room temperature saturated magnetic moment clearly shows two stable states which are reversible by switching the ferroelectric polarization. The observed effect, which is about 15% in strength can be modulated over several cycles. This first demonstration of electric field effect in an oxide based diluted ferromagnetic insulator system provides evidence of its intrinsic nature. Furthermore, the ability of electric field modulation of ferromagnetism is very promising for next-generation multi-functional electronic devices. Possible mechanisms for electric field induced modulation of insulating ferromagnetism are discussed. This work was supported by DARPA SpinS program (through US-ONR) and the NSF-MRSEC (DMR 00-80008) at Maryland. The PLD and RBS facilities used in this work are shared experimental facilities (SEF) supported in part under NSF-MRSEC.