Abstract
The ordered double perovskites Sr2CrOsO6 and Ca2CrOsO6 have been synthesized and characterized with neutron powder diffraction, electrical transport measurements, and high field magnetization experiments. As reported previously Sr2CrOsO6 crystallizes with R3¯ symmetry due to a-a-a- octahedral tilting. A decrease in the tolerance factor leads to a-a-b+ octahedral tilting and P21/n space group symmetry for Ca2CrOsO6. Both materials are found to be ferrimagnetic insulators with saturation magnetizations near 0.2 μB. Sr2CrOsO6 orders at 660 K while Ca2CrOsO6 orders at 490 K. Variable temperature magnetization measurements suggest that the magnetization of the Cr3+ and Os3+ sublattices have different temperature dependences in Sr2CrOsO6. This leads to a non-monotonic temperature evolution of the magnetic moment. Similar behavior is not seen in Ca2CrOsO6. Both compounds have similar levels of Os/Cr antisite disorder, with order parameters of η=80.2(4)% for Sr2CrOsO6 and η=76.2(5)% for Ca2CrOsO6, where η=2θ-1 and θ is the occupancy of the osmium ion on the osmium-rich Wyckoff site.
Original language | English |
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Pages (from-to) | 46-52 |
Number of pages | 7 |
Journal | Journal of Solid State Chemistry |
Volume | 238 |
DOIs | |
State | Published - Jun 1 2016 |
Funding
Support for this research was provided by the Center for Emergent Materials an NSF sponsored Materials Research Science and Engineering Center ( DMR-1420451 ). Additional support was provided by the U.S. Department of Energy, Office of High Energy Physics under Grant number DE-FG02-95ER40900 and DE-SC0001304 (magnetic characterization). A portion of this work was performed at the National High Magnetic Field Laboratory, which is supported by National Science Foundation Cooperative Agreement no. DMR-1157490 and the State of Florida . A portion of this research was carried out at Oak Ridge National Laboratory's Spallation Neutron Source and High Flux Isotope Reactor, which is sponsored by the U.S. Department of Energy, Office of Basic Energy Sciences . The authors thankfully acknowledge Ashfia Huq and Pamela Whitfield for experimental assistance with POWGEN data collection.
Keywords
- Magnetism
- Neutron powder diffraction
- Osmate
- Perovskite