Interface-Driven Ferromagnetism within the Quantum Wells of a Rare Earth Titanate Superlattice

R. F. Need, B. J. Isaac, B. J. Kirby, J. A. Borchers, S. Stemmer, and Stephen D. Wilson

Phys. Rev. Lett. 117, 037205 – Published 12 July 2016

Abstract

Here we present polarized neutron reflectometry measurements exploring thin film heterostructures composed of a strongly correlated Mott state, ${GdTiO}_{3}$ , embedded with ${SrTiO}_{3}$ quantum wells. Our results reveal that the net ferromagnetism inherent to the Mott ${GdTiO}_{3}$ matrix propagates into the nominally nonmagnetic ${SrTiO}_{3}$ quantum wells and tracks the magnetic order parameter of the host Mott insulating matrix. Beyond a well thickness of 5 SrO layers, the magnetic moment within the wells is dramatically suppressed, suggesting that quenched well magnetism comprises the likely origin of quantum critical magnetotransport in this thin film architecture. Our data demonstrate that the interplay between proximate exchange fields and polarity-induced carrier densities can stabilize extended magnetic states within ${SrTiO}_{3}$ quantum wells.

Received 17 March 2016

DOI:https://doi.org/10.1103/PhysRevLett.117.037205

Physics Subject Headings (PhySH)

Ferromagnetism Magnetic order

Magnetic multilayers Multilayer thin films Oxides Two-dimensional electron gas

Neutron reflectometry

Condensed Matter, Materials & Applied Physics

Authors & Affiliations

R. F. Need¹, B. J. Isaac¹, B. J. Kirby², J. A. Borchers², S. Stemmer¹, and Stephen D. Wilson^1,*

¹Materials Department, University of California, Santa Barbara, California 93106-5050, USA
²NIST Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg, Maryland 20899-6100, USA