(Color online) MPS (26 kHz, 50 mT/μ0) signal parameters of MNPs, field frozen (10 mT/μ0) along different directions with respect to the MPS applied field. (a) χdiff and (b) integrated m(H) curves. MPS (26 kHz, 50 mT/μ0) signal parameters of MNPs, frozen in different magnetic fields along parallel orientation: (c) χdiff and (d) m(H) curves. MPS (50 mT/μ0, different frequencies) signal parameters of MNPs, frozen in 5 mT/μ0 along parallel orientation: (e) diff and (f) m(H) curves.