TY - JOUR
T1 - An X- and Q-band Fe3+ EPR study of nanoparticles of magnetic semiconductor Zn1-xFexO
AU - Misra, Sushil K.
AU - Andronenko, S. I.
AU - Thurber, A.
AU - Punnoose, A.
AU - Nalepa, A.
PY - 2014/8
Y1 - 2014/8
N2 - EPR studies on two types of nanoparticles of Fe3+ doped, 0.1-10%, ZnO, NL and QJ, prepared using similar chemical hydrolysis methods, in diethylene glycol, and in denatured ethanol solutions, respectively, were carried out at X-band (~9.5 GHz) at 77 K and at Q-band (~34.0 GHz) at 10, 80, and 295 K. To interpret the experimental results, EPR spectra were simulated by exact diagonalization of the spin-Hamiltonian matrix to identify the Fe ions at different magnetically active sites in these samples. The simulation for NL samples revealed that they contained (i) Fe3+ ions, which substituted for Zn ions, the zero-field splitting (ZFS) parameter which has a large distribution over the sample due to oxygen vacancies in the second coordination sphere; (ii) EPR signal from surface oxygen defects; and (iii) ferromagnetically (FM) coupled Fe ions with concentration of Fe more than 1%. The EPR spectra for QJ samples are very different from those for NL samples, exhibiting only rather intense FM EPR lines. The FM and EPR spectra in NL and/or QJ samples are found to vary strongly with differences in the surface morphology of nanoparticles.
AB - EPR studies on two types of nanoparticles of Fe3+ doped, 0.1-10%, ZnO, NL and QJ, prepared using similar chemical hydrolysis methods, in diethylene glycol, and in denatured ethanol solutions, respectively, were carried out at X-band (~9.5 GHz) at 77 K and at Q-band (~34.0 GHz) at 10, 80, and 295 K. To interpret the experimental results, EPR spectra were simulated by exact diagonalization of the spin-Hamiltonian matrix to identify the Fe ions at different magnetically active sites in these samples. The simulation for NL samples revealed that they contained (i) Fe3+ ions, which substituted for Zn ions, the zero-field splitting (ZFS) parameter which has a large distribution over the sample due to oxygen vacancies in the second coordination sphere; (ii) EPR signal from surface oxygen defects; and (iii) ferromagnetically (FM) coupled Fe ions with concentration of Fe more than 1%. The EPR spectra for QJ samples are very different from those for NL samples, exhibiting only rather intense FM EPR lines. The FM and EPR spectra in NL and/or QJ samples are found to vary strongly with differences in the surface morphology of nanoparticles.
KW - Dilute magnetic semiconductor
KW - EPR
KW - Nanoparticle
KW - Q-band
KW - X-band
KW - ZnO
UR - https://www.scopus.com/pages/publications/84898656690
U2 - 10.1016/j.jmmm.2014.03.031
DO - 10.1016/j.jmmm.2014.03.031
M3 - Article
AN - SCOPUS:84898656690
SN - 0304-8853
VL - 363
SP - 82
EP - 87
JO - Journal of Magnetism and Magnetic Materials
JF - Journal of Magnetism and Magnetic Materials
ER -