@article{oai:oist.repo.nii.ac.jp:00001939,
 author = {Bohra, Murtaza and Alman, Vidya and Showry, Arun and Singh, Vidyadhar and Diaz, Rosa E. and Sowwan, Mukhles and Grammatikopoulos, Panagiotis},
 issue = {51},
 journal = {ACS Omega},
 month = {Dec},
 note = {Annealing is a valuable method for fine-tuning the ultrasmall magnetic properties of alloy nanoparticles (NPs) by controlling their sizes, modifying their surfaces, and affecting their magnetic interactions. Herein, we study the effect of moderate annealing (450°C) on strongly interacting NiCr nanoparticle assemblies (0 <= atom % Cr ≤ 15) immediately after deposition. Concurrent temperature-dependent electron microscopy and magnetization data demonstrate the interplay of two competing factors, namely, enhanced particle aggregation and element-specific surface segregation, on the magnetic properties, with the former boosting and the latter suppressing them. Strong interparticle interactions can lead to a magnetic response different from that of superparamagnetic particles, namely, from canonical spin-glass (0 atom % Cr) to correlated spin-glass (5-15 atom % Cr) behavior below higher spin-glass transition temperatures T-g (20-350 K). The observation of "high-field susceptibility" below cryogenic temperatures (≤20 K) is ascribed to the presence of inhomogeneity/defects caused by Cr segregation. This work emphasizes the necessity of taking into account the delicate balance of such competing factors to understand the magnetic properties of nanoparticulate samples.},
 pages = {32883--32889},
 title = {Aggregation vs Surface Segregation: Antagonism over the Magnetic Behavior of NiCr Nanoparticles},
 volume = {5},
 year = {2020}
}