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BYInvestigating the superhyperfine interactions (SHFI) of iron-group ions with 3+ 2+surrounding lithium nuclei the substitutional models of Fe , Cr3+, and Mn in a -L i I 0 3 single crystals have been determined /I, 2/. It was shown that iron-group ions substitute Li' in the lattice and the excess charge compensation is performed by two nearest lithium vacancies along the z-axis for trivalent ions, o r by one nearest lithium vacancy for divalent ions.determined with the method of radiofrequency discrete saturation (RFDS) /3/.The measurements were carried out in the X-band at liquid helium temperatures. The concentration of co2+ in the samples was about 2 . 5~1 O -~ mol%.The EPR spectra of Co2+ can be described in t e r m s of the axial spinHamiltonian with S = 1/2,1 = 1/2, gll = 3.687 + 0.002, g, = 4.656 + 0.003, A,, = (3.59 + -0.02)mT, hexagonal crystal c-axis. The'se data are quite near to those given in /4/.t o crystals z-axis and the angular dependence of these spectra at rotation of 3 in the plane perpendicular to 2 have been investigated.The presence of the lines of three lithium nuclei in the RFDS spectra which are independent of rotation about the crystal z-axis proves that the Co2+ ion substitutes Li' in the lattice and the excess charge compensation is realized by the nearest lithium vacancy along the z-axis.As in the c a s e of Cr3+, Fe3+, and MnIn the present note we adduce the structure of Co2+ paramagnetic centers A, = (6.24 + -0.02)mT and the z-axis directed along theThe RFDS spectra at the orientation of the external magnetic field 8 parallel 2+ in LiI03 it was found that the measuredRFDS frequencies were near to those calculated in pure dipolar approximation for the undistorted lattice, deviations being caused by local distortions of the lattice. However, in the c a s e of Co2' in LiI03 the t r a c e s of the determined 1 ) prospekt Chavchavadze 3, 380028 Tbilisi, USSR.

The possibility to control the magnetic properties of a material with an electric field at room temperature is highly desirable for modern applications. Moreover, a coupling between magnetic and electric orders within a single material presenting a wide range of exceptional physical properties, such as bismuth iron garnet (BIG), may lead to great advances in the field of spintronic applications. In particular, the combination of the magnetoelectric (ME) coupling with the low damping of spin waves in BIG can allow the control and manipulation of spin waves by an electric field in magnonic devices. Here we report the unambiguous observation of linear magnetoelectric coupling above 300 K in BIG using ferromagnetic resonance technique with electric field modulation. The measured coupling value is comparable with that observed for prototypal magnetoelectric Cr2O3. On the basis of our experimental results, the strength of this linear ME coupling is directly linked to the presence of bismuth ions inducing strong spin orbit coupling and to the appearance of local magnetic inhomogeneities related to the magnetic domain structure. The unprecedented combination of magnetic, optical and magnetoelectrical properties in BIG is expected to trigger significant interest for technological applications as well as for theoretical studies.

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An original two-stage liquid-phase hot explosive compaction (HEC) procedure of Mg-B precursors above 900 • C provides the formation of superconductivity MgB 2 phase in the whole volume of billets with maximal T c = 38.5 K without any further sintering. The liquid-phase HEC strongly increases the solid-state reaction rate similar to photostimulation, but in this case, due to the high penetrating capability of shock waves in a whole volume of cylindrical billets and consolidation of MgB 2 precursors near to theoretical density allows one to produce bulk, longbody cylindrical samples important for a number practical applications.