Antisites driven magnetic transition study in La2NiMnO6

La2NiMnO6 is a unique compound of multiferroics that exhibits two magnetic transitions of Curie points TC1 and TC2 below room temperature on a partial conversion of charge carriers, Ni2+ → Ni3+ and Mn4+→ Mn3+, stabilized with O2- vacancies in distorted octagons in a double perovskite of a spin cluster (glass), wherein the spins freezing at a critical Tg point at lower temperatures. The peak temperature and irreversibility temperature shifted to the lower temperature. The dc magnetization M (T) measurements indicate random ferromagnetic and antiferromagnetic interactions and multiple magnetic transitions. The critical slowing properties signify the spin-glass nature proved by the thermomagnetic relaxation measure.

SrTiO3—Glimpses of an Inexhaustible Source of Novel Solid State Phenomena

The purpose of this selective review is primarily to demonstrate the large versatility of the insulating quantum paraelectric perovskite SrTiO3 explained in “Introduction” part, and “Routes of SrTiO3 toward ferroelectricity and other collective states” part. Apart from ferroelectricity under various boundary conditions, it exhibits regular electronic and superconductivity via doping or external fields and is capable of displaying diverse coupled states. “Magnetoelectric multiglass (Sr,Mn)TiO3” part, deals with mesoscopic physics of the solid solution SrTiO3:Mn2+. It is at the origin of both polar and spin cluster glass forming and is altogether a novel multiferroic system. Independent transitions at different glass temperatures, power law dynamic criticality, divergent third-order susceptibilities, and higher order magneto-electric interactions are convincing fingerprints.

Twinned olivenite from Cap Garonne, Mine du Pradet – structure and magnetic behavior

Systematically twinned olivenite (Cu2(AsO4)OH) single crystals from Cap Garonne, Mine du Pradet, France, were studied by X-ray diffraction: P 21/n, a = 822.69(6) pm, b = 861.88(9) pm, c = 594.06(9) pm, β = 90.000(6)°, wR = 0.0224, 1621 F2 values, 79 variables and a domain ratio of 0.501(1)/0.499(1). The temperature dependence of the magnetic susceptibility was well reproduced with a square-spin cluster model and an antiferromagnetic spin-exchange parameter of J/kB = 157(3) K.

Использование усреднения по полям взаимодействия для построения приближенных методов в модели Изинга разбавленного магнетика

The method of averaging over interaction fields has been analyzed as applied to the problems of statistical physics. This method has been theoretically justified as applied to a spin cluster. Based on the general relations obtained, approximate solutions for the bond-diluted Ising model are found. These approximate solutions are compared with the exact solution for a one-dimensional chain of bond-diluted Ising spins.