ИСТИНА

Recently we have discovered the slow magnetic relaxation and typical for SIM magnetic behavior in calcium, strontium and barium phosphates with apatite structure containing copper, cobalt and dysprosium ions. Such compounds represent a well isolated paramagnetic ions confined in a stable diamagnetic inorganic phosphate matrix that provides highly anisotropic environment for d- or f-metal ions: [O-M-O] for 3d-metals and [Dy-O]+ for dysprosium so creating nearly ideal conditions for the SIM properties emergence. Furthermore this structure allows to increase the distance between paramagnetic atoms by playing with the concentration that could enlarge the relaxation time as we have demonstrated by copper and cobalt containing samples. Another opportunity to improve magnetic properties is playing with the kind of nonmagnetic matrix cations and consequently the crystal field: thus we have improved a magnetization reversal energy barrier for cobalt compounds by changing calcium for barium cation in the phosphate matrix. Additionally it is possible to influence on the oxidation state of paramagnetic metals by the synthesis conditions as we have demonstrated by the copper containing compounds. This approach allows us to obtain compounds with SIM properties containing copper, cobalt and dysprosium as paramagnetic atom that are characterized by very high magnetization reversal energy barrier up to 100, 390 and 1040 cm-1 respectively.