Exchange bias effect in alloys and compounds

The phenomenology of exchange bias effects observed in structurally single-phase alloys and compounds but composed of a variety of coexisting magnetic phases such as ferromagnetic, antiferromagnetic, ferrimagnetic, spin-glass, cluster-glass and disordered magnetic states are reviewed. The investigations on exchange bias effects are discussed in diverse types of alloys and compounds where qualitative and quantitative aspects of magnetism are focused based on macroscopic experimental tools such as magnetization and magnetoresistance measurements. Here, we focus on improvement of fundamental issues of the exchange bias effects rather than on their technological importance

Tetrahydrated bis(monoaqua-bis(ethylenediamine)copper(II))-diaqua-bis(ethylenediamine)copper(II) dicitrate

The crystals of the first copper(II) ethylenediamine complex containing citrate anion have been prepared and characterized. Despite the archetypical character of the copper(II) ethylenediamine complexes, some structural peculiarities were found to be interesting since they are quite rare even among the mentioned type of the complex compounds i.e. a presence of both mono and diaqua-bis(ethylenediamine)copper(II) cations together in the same crystal structure, intramolecular hydrogen bonding of the citric anion, cis,trans-configuration of the citric anion and the disordered C-C bond of the ethylenediamine molecule in the monoaquabis(ethylenediamine)copper(II) cation, which in fact is a co-existence of two energetically close dd and dk conformers. The Raman as well as FTIR spectra were recorded and discussed. Finally, the magnetic measurements have shown paramagnetic behavior of the prepared complex in a wide range of temperatures

Structural and magnetic properties of nanocrystalline bismuth manganite obtained by mechanochemical synthesis

We have studied the formation of BiMnO3 (BMO) nanocrystalline perovskite powder produced by high-energy milling of the constituent oxides. The crystal structure and the amount of crystalline and amorphous phases in the powder as a function of the milling time were determined with XRPD using Rietveld refinement. BMO perovskite formed directly from highly activated nano-sized constituent oxides after 240 min of milling and subsequently grew during prolonged milling. The morphology, structure, and chemical composition of the powder were investigated by SEM and TEM. A clear ferromagnetic transition was observed at T C ~66 K for a sample milled for 240 min and increased with milling time. The magnetic hysteresis behavior is similar to that of a soft ferromagnet. The magnetic properties of the obtained BMO powders were found to change as a function of milling time in a manner consistent with variations in the nanocomposite microstructure

Effect of Pressure on Magnetic Properties of (NH3OH)2CoF4(NH_3OH)_2CoF_4 Fluoro-Metal Complex

Effect of pressure on magnetic properties of a bulk fluoro-metal complex $(NH_3OH)_2MF_4$ was studied. Magnetization measurements suggest that a ferromagnetic transition at $T_{C1}$ = 47 K is followed by a ferrimagnetic one at $T_{C2}$ = 3 K. Both transition temperatures are pressure dependent with the pressure coefficients $dT_{C1}$/ dp = - 2.6 K/GPa and $dT_{C2}$/ dp = 0.26 K/GPa. The opposite sign of the coefficients is an additional indication of a different nature (ferromagnetic/antiferromagnetic) of these two transitions. The effect of pressure on low field magnetization and exchange bias phenomena is small but still visible