Specific heat (left axis) and magnetization (right axis) data measured in the Fe2.98Al0.02O4. Solid line indicates specific heat divided by the temperature as a function of temperature. The integral of the specific heat peak yields change of the molar entropy at the transition. Open circles indicate magnetization data. A half degree hysteresis is clearly visible in the data. Straight dashed lines indicate the width of the transition. We determined the transition temperature to be in the center between the onset of the magnetization drop and the end of the drop.
Low temperature Raman spectra of Fe2.98Al0.02O4 at 6.4 GPa. Dashed line corresponds to 45 K-spectrum, dotted line corresponds to 40 K-spectrum, and solid line corresponds to 37 K-spectrum. Arrows indicate transition markers. The 45 K-spectrum corresponds to the low temperature phase. The 37 K spectrum corresponds to the high temperature phase. The 40 K-spectrum corresponds to a mixed state.
Verwey transition temperature as a function of pressure. Open symbols indicate low temperature phase; filled symbols indicate the high temperature phase. Circles correspond to Al-doped sample, diamonds indicate our previously published data24 in pure magnetite, and triangles represent the XRPD data of Rozenberg et al. 25 Error bars indicate typical uncertainty of the technique. Note that the pressure error bars are smaller than the symbols. Dashed lines indicate suggested phase separation PT equilibrium lines.
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