Modified magnetic ground state in NiMn2O4 thin films
We demonstrate the stabilization of a magnetic ground state in epitaxial NiMn2O4 (NMO) thin films not observed in their bulk counterpart. Bulk NMO exhibits a magnetic transition from a paramagnetic phase to a collinear ferrimagnetic moment configuration below 110 K and to a canted moment configuration below 70 K. By contrast, as-grown NMO films exhibit a single magnetic transition at 60 K and annealed films exhibit the magnetic behavior found in bulk. Cation inversion and epitaxial strain are ruled out as possible causes for the new magnetic ground state in the as-grown films. However, a decrease in the octahedral Mn{sup 4+}:Mn{sup 3+} concentration is observed and likely disrupts the double exchange that produces the magnetic state at intermediate temperatures. X-ray magnetic circular dichroism and bulk magnetometry indicate a canted ferrimagnetic state in all samples at low temperature. Together these results suggest that the collinear ferrimagnetic state observed in bulk NMO at intermediate temperatures is suppressed in the as grown NMO thin films due to a decrease in octahedral Mn{sup 4+} while the canted moment ferrimagnetic ordering is preserved below 60 K.
- Research Organization:
- Ernest Orlando Lawrence Berkeley National Laboratory, Berkeley, CA (US)
- Sponsoring Organization:
- Advanced Light Source Division
- DOE Contract Number:
- AC02-05CH11231
- OSTI ID:
- 1000055
- Report Number(s):
- LBNL-4036E
- Journal Information:
- Physical Review B, Journal Name: Physical Review B Journal Issue: 14 Vol. 82; ISSN 1098-0121; ISSN 1550-235X
- Country of Publication:
- United States
- Language:
- English
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