Abstract
Large configurational disorder in compositionally complex ceramics can lead to unique functional properties that deviate from traditional rules of alloy mixing. In recent years, compositionally complex oxides (CCOs) have shown intriguing magnetic behavior including long-range order, enhanced magnetic exchange couplings, and mixed phase magnetic structures. This work focuses on how large local spin disorder affects magnetic ordering in a CCO. Specifically, we investigated the A-site alloyed perovskite, (Y0.2La0.2Pr0.2Nd0.2Tb0.2)MnO3, or (5A)MnO3, using a combination of bulk magnetometry, synchrotron X-ray diffraction, and temperature-dependent neutron diffraction. The five A-site ions have an average spin and ionic radius nearly equal to that of Nd3+ ions, which minimizes structural distortions and allows for an understanding of the local spin disorder effects through a direct comparison with NdMnO3. Our magnetometry data show that (5A)MnO3 exhibits two distinct phase transitions associated with the A-site and B-site sublattices, as seen in NdMnO3, as well as the presence of domain pinning and exchange bias at low temperature, suggesting a mixed phase magnetic ground state, as seen in other magnetic CCOs. Neutron powder diffraction shows clear long-range antiferromagnetic ordering below 67 K and refines to a Pn′ma′ magnetic structure at low temperature, in excellent agreement with the well-studied behavior of NdMnO3. The two most notable differences in (5A)MnO3 magnetism apparent from our data are a slight suppression of the B-site ordering temperature, which is explained by a smaller Mn-O-Mn bond angle in (5A)MnO3 than NdMnO3, and the presence of a magnetic susceptibility transition above the B-site ordering, which could indicate the formation of a cluster glass but requires further study. This work demonstrates a general method of isolated investigation of size and spin disorder in CCOs and motivates future work using local structure probes to better understand the effects of nanoscale clustering and local spin disorder in magnetic CCOs.
| Original language | English |
|---|---|
| Pages (from-to) | 13474-13484 |
| Number of pages | 11 |
| Journal | Journal of Materials Chemistry C |
| Volume | 12 |
| Issue number | 34 |
| DOIs | |
| State | Published - Jul 30 2024 |
Funding
This research used resources at the Spallation Neutron Source, a DOE Office of Science User Facility operated by the Oak Ridge National Laboratory. Neutron beam time was allocated to POWGEN on proposal number IPTS-25103.1. This research also used resources of the Advanced Photon Source, a U.S. Department of Energy (DOE) Office of Science user facility operated for the DOE Office of Science by Argonne National Laboratory under Contract No. DE-AC02-06CH11357. X-Ray beam time was allocated to 11-BM on proposal number 75192. Funding for this work came in part from UF Research. The authors would also like to thank Sarathy K. Gopalkrishnan and Anna Ipatova for helpful translation of old French papers, and Amlan Biswas and Mark W. Meisel for helpful discussions regarding possible origins of the high-temperature susceptibility transition.