DigitalCommons@University of Nebraska - Lincoln

Title

Surface anisotropy and magnetic freezing of MnO nanoparticles

Authors

Marco Morales Torres, University of Nebraska - Lincoln
Ralph Skomski, University of Nebraska-Lincoln
Shannon Fritz, University of Nebraska - Lincoln
G. Shelburne, University of Nebraska - Lincoln
Jeffrey E. Shield, University of Nebraska - Lincoln
Ming Yin, Columbia University, New York City, New York
Stephen O'Brien, Columbia University, New York City, New York
Diandra Leslie-Pelecky, University of Nebraska -- Lincoln

Document Type

Article

Date of this Version

April 2007

Comments

Published by American Physical Society. Phys. Rev. B 75, 134423 2007. http://prb.aps.org. Copyright © 2007 American Physical Society. Permission to use.

Nanoparticles of bulk antiferromagnets often exhibit ferromagnetic behavior due to uncompensated surface spins. The peak temperature in the zero-field-cooled magnetization of MnO—in contrast to other antiferromagnetic nanoparticles—has anomalous behavior, shifting to higher temperatures with decreasing nanoparticle size. We attribute this behavior to surface anisotropy enhanced by the specific occupancy of 3d levels in Mn, which produces a high-spin–low-spin transition not present in NiO nanoparticles.