Abstract
Dy–Mg silicate Dy8Mg2(SiO4)6O2 has been prepared by high-temperature solid state reaction. It has an apatite type structure (P63/m) with the Dy atoms fully occupying the 6h site and being in random distribution with the Mg atoms at the 4f site. The compound reveals dual magnetization relaxation with widely varying contributions from fast (FR) and slow (SR) relaxation paths controlled by field and temperature. The SR path is stabilized by a strong magnetic field, exhibits a weak dependence of relaxation time τ on field and temperature, and sustains large τ of a few seconds up to a temperature of 40 K and under a field of 50 kOe. The analysis of the electronic structure and comparison with the known Dy-doped phosphate apatites suggests that the Orbach and Raman processes are suppressed.
Highlights
The SR path is stabilized by a strong magnetic field, exhibits a weak dependence of relaxation time s on field and temperature, and sustains large s of a few seconds up to a temperature of 40 K and under a field of 50 kOe
The analysis of the electronic structure and comparison with the known Dy-doped phosphate apatites suggests that the Orbach and Raman processes are suppressed
In our recent work we showed a similar behavior of the SR path for Tb3+ in Ca10ÀxTbx(PO4)6(OH1Àx/2Àd)[2] which persisted in the compound with x 1⁄4 0.5 and was absent in diluted one with x 1⁄4 0.1.29 As was discussed above, the SR path for Dy8Ca2(SiO4)6O2 is similar to that observed in the present study
Summary
To date hundreds of coordination compounds of open shell dand f-metals have been shown to exhibit magnetic bistability of a lone metal ion and are referred to as single ion magnets (SIMs) with potential applications in super-dense information recording, molecular electronics, spintronics, and quantum computing.[1,2,3,4,5,6] Their key parameters – the energy barrier for magnetization reversal Ueff and magnetization blocking temperature Tb (the temperature at which the hysteresis loop closes) – lately have been strongly improved and currently approach 1540 cmÀ1 and 80 K, respectively.[7,8,9,10] Open shell metal ions embedded in a diamagnetic ceramic inorganic matrix constitute a special class of such materials.[11]. As this oxygen atom provides the largest contribution to crystal eld anisotropy[18] we expect that the magnetic anisotropy in the Dy–Mg compound at the M2 site is higher.
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