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Hysteresis Loop Shifts in Magnetic Field Cooled FeOOH Nanoparticles

Published online by Cambridge University Press:  21 February 2011

M.S. Seehra ,
Paromita Roy  and
A. Manivannan
M.S. Seehra
Affiliation:
Physics Department, West Virginia University, Morgantown, WV 26506-6315
Paromita Roy
Affiliation:
Physics Department, West Virginia University, Morgantown, WV 26506-6315
A. Manivannan
Affiliation:
Physics Department, West Virginia University, Morgantown, WV 26506-6315
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Abstract

Measurements of the magnetization M as a function of temperature (5K - 300K) and applied magnetic field H (up to 50 kOe) in 30 Å particles of FeOOH are reported. M increases with decreasing T, peaking at TB = 65 K below which the ZFC (zero-field-cooled) and the FC (field-cooled) data separate. Hysteresis loop measured at 10 K for ZFC shows an open loop up to 40 kOe with coercivity = 2 kOe. For the FC case, the loop shifts and the loop-shift increases with the cooling field ItL, approaching saturation above Hc = 20 kOe. From the variation of M vs H above TB, a magnetic moment/particle μp = 300 μB is determined. These results suggest that the FeOOH nanoparticles have an antiferromagnetically ordered core with uncompensated surface spins yielding μp and the surface spins order in a spin-glass-like state below TB, possibly due to interparticle interactions.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 581: Symposium F – Nanophase & Nanocomposite Materials II , 1999 , 511
Copyright
Copyright © Materials Research Society 2000

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