title: Large magnetization and frustration switching of magnetoresistance in the double-perovskite ferrimagnet Mn2FeReO6.
abstract: Ferrimagnetic A2 BB'O6 double perovskites, such as Sr2 FeMoO6 , are important spin-polarized conductors. Introducing transition metals at the A-sites offers new possibilities to increase magnetization and tune magnetoresistance. Herein we report a ferrimagnetic double perovskite, Mn2 FeReO6 , synthesized at high pressure which has a high Curie temperature of 520 K and magnetizations of up to 5.0 μB which greatly exceed those for other double perovskite ferrimagnets. A novel switching transition is discovered at 75 K where magnetoresistance changes from conventional negative tunneling behavior to large positive values, up to 265 % at 7 T and 20 K. Neutron diffraction shows that the switch is driven by magnetic frustration from antiferromagnetic Mn(2+) spin ordering which cants Fe(3+) and Re(5+) spins and reduces spin-polarization. Ferrimagnetic double perovskites based on A-site Mn(2+) thus offer new opportunities to enhance magnetization and control magnetoresistance in spintronic materials.
authors: Centre for Science at Extreme Conditions (CSEC) and School of Chemistry, University of Edinburgh, Mayfield Road, Edinburgh EH9 3JZ (UK).
authors: Angel M
authors: AM
authors: Arévalo-López
authors: Centre for Science at Extreme Conditions (CSEC) and School of Chemistry, University of Edinburgh, Mayfield Road, Edinburgh EH9 3JZ (UK).
authors: Graham M
authors: GM
authors: McNally
authors: Centre for Science at Extreme Conditions (CSEC) and School of Chemistry, University of Edinburgh, Mayfield Road, Edinburgh EH9 3JZ (UK). j.p.attfield@ed.ac.uk.
authors: J Paul
authors: JP
authors: Attfield
keywords: ferrimagnetic double perovskites; high-pressure chemistry; magnetic properties; magnetoresistance; perovskite phases