Structural response to the magnetic pre-ordering in LiFeSi2O6

Abstract

We investigate the temperature evolution of the structural parameters of potential ferrotoroidic LiFeSi2O6 compound across structural and magnetic phase transitions. The structural transition (TS)is around 220K and the paramagnetic to antiferromagnetic transition (TN ) is around 18K. The lattice parameters exhibit unusual temperature dependence and based on its behaviour, the experimental results can be divided into 3 regions.In region I (300K to 240K), the cell parameters are mainly governed by mere thermal effect. As the compound enters region II (below 240K to 50K), the lattice parameters show non linear behaviour. In this region, the exchange pathways that lead to the magnetic interactions within and between the Fe-Fe chains do not show significant response.The region III (below 50K) is dominated by the magnetic contribution where we observe setting up of intra and inter-chain magnetic interaction. This behaviour is unlike other low dimensional compounds like Ca3Co2O6, Sr3NiRhO6, MnTiO3 etc. thereby suggesting the magnetism in LiFeSi2O6 is of three dimensional nature. The present results will be helpful in understanding the evolution of the spin rings that give rise to net toroidal moment and hence its multiferroic behaviour.PACS numbers:

A sustainable reaction process for phase pure LiFeSi2O6 with goethite as an iron source

“…This finding is in a good agreement with previous results, i.e. variation of T N between 17.5 and 20.8 K [14,30]. We note, however, that the samples of the former were obtained by a solid state process by heating at 900°or 950 °C in polycrystalline form for more than one month [14], or even at T = 1300 °C under pressure P = 3 GPa provided single crystal [30] and the latter a natural mineral donated by the British Museum of Natural History.…”

“…Our product contain a small amount of silica, as shown in Table 1, which does not influence its magnetic properties. Note that the samples prepared by Mauria et al [14],…”

“…Conventional ceramic preparative methods of LFS are laborious, with prolonged heating time and repeated sintering [13,14], or pre liminary hydrothermal processes [11,12]. It is recognized that preliminary mechanical activation of the starting mixture enables de crease of heating temperature and crystallite size [15].…”