Open AccessModified Magnetic Ground State in Nimn (2) O (4) Thin Films
Author(s) -
Brittany B. Nelson-Cheeseman,
R.V. Chopdekar,
J.M. Iwata,
M.F. Toney,
E. Arenholz,
Y. Suzuki
Publication year - 2012
Language(s) - English
Resource type - Reports
DOI - 10.2172/1049759
Subject(s) - ferrimagnetism , magnetic moment , condensed matter physics , paramagnetism , ground state , materials science , magnetic circular dichroism , magnetometer , magnetic domain , thin film , nuclear magnetic resonance , crystallography , magnetization , chemistry , physics , magnetic field , nanotechnology , atomic physics , spectral line , quantum mechanics , astronomy
The authors demonstrate the stabilization of a magnetic ground state in epitaxial NiMn{sub 2}O{sub 4} (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 T. 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