512Multiferroics are promising materials for the pro duction of elements of devices transforming magnetic signals into electric ones. This property is due to the large magnetoelectric effect observed in a number of compounds, in particular, in RMn 2 O 5 manganites (R is a rare earth element) in which the antiferromag netic and ferroelectric orders coexist at low tempera tures [1,2]. Their crystal structure corresponds to an orthorhombic lattice and was studied in, e.g., [3] [4] and, simultaneously with a weak anomaly of the magnetic susceptibility χ [5], the temperature dependence of the dielectric constant ε(T) has a sharp peak at the temperature T FE1 = 35 K close to the Néel temperature [1,5,6]. A shift of the Raman spectrum is also observed in this range [7]. It had been found that these phenomena are due to the ferroelectric transition stimulated by the appearance of the long range magnetic order at the temperature T N = 40 K, which results in an additional distortion of the positions of the Mn 3+ ions along the a axis. The next phase transition occurs at the temperature T FE2 = 22 K and is accompanied by an increase in the inten sity of the magnetic scattering of neutrons [4], a weak anomaly in the magnetic susceptibility χ [1], a sharp peak of the dielectric constant [1,5,6], and a jump in the intensity of the passage of millimeter electromag netic radiation [6]. The analysis of the data indicates that this structure phase transition is initiated by the rotation of the magnetic moments of the Mn 3+ and Mn 4+ ions and by the shift of the Mn 4+ ions along the c axis.A wide anomaly in the temperature dependence of the dielectric constant ε(T) was also revealed in the temperature range T = 13-23 K [1,[4][5][6], which is correlated with the bends in the temperature depen dence of the magnetic susceptibility χ(T) and with the features of the magnetic scattering of neutrons. These effects can imply the existence of magnetic and struc tural inhomogeneities.Unusual phenomena were also revealed at high temperatures (at 100-130 K), but they likely have another nature and are attributed to the existence of limited correlated magnetic regions [5].The experimental data considered above demon strate a strong correlation between the electric and magnetic phenomena (magnetoelectric effect) and indicate the relation between the structural and mag netic properties.In this work, the comparative muon spin relax ation ( Sciences, Gatchina, 188300 Russia * e mail: vsiloa@pnpi.spb.ru b Ioffe Physicotechnical Institute, Russian Academy of Sciences, Politekhnicheskaya ul. 26, St. Petersburg, 194021 Russia Received March 26, 2010 The magnetic properties of the EuMn 2 O 5 multiferroic (samples consisting of single crystals and ceramic sam ples) have been investigated by the muon spin relaxation (µSR) method in the temperature range of 10-300 K. Below the magnetic ordering temperature T N = 40 K, the loss of the polarization of muons and the effect of the external magnetic field have been observed. Both phenomena can be expl...