engleski

Study of the local magnetic field fluctuations near surface of the nanomagnets Mn12-Ac by pulsed EPR

In the present study, a pulse electron paramagnetic spectroscopy (EPR) and N-methylphenazinium-tetracyanoquinodimethane (NMP-TCNQ) paramagnetic probe have been employed for detecting transversal local magnetic field fluctuation at the microsecond time scale in the vicinity of surface of single molecular magnets [Mn12O12(CH3COO)16(H2O)4].2CH3COOH.4H2O (Mn12-Ac). By employing Electron spin echo detected EPR (ED-EPR), it can be shown that beside dominant sharp signal, previously detected by Continues wave EPR (CW-EPR), one obtains an additional broad component of the NMP-TCNQ signal. The broad signal component represents an inhomogeneously broadened line. The homogeneous components of this line are narrower than the CW-EPR line and its linewidth, δ , can be approximated with the measured phase memory time, TM, (1/TM~1/T2=δ ). Thus, by measuring of TM which originates from the broad inhomogeneus part of NMP-TCNQ spectrum, shifted due to local field of Mn12-Ac, one expects to detect the effect of fluctuations of this field. The obtained transversal field fluctuation process is at the microsecond time scale and can be described by an Arrheniuus low with corresponding activation energy (E=44&plusmn ; ; 7K) in the high temperature interval (10-25K).

Mn12-Ac; Pulse EPR

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