he magnetic properties of synthetic lepidocrocite (g-FeOOH) were investigated between 5 and 300 K. The purity of the samples was verified by X-ray diffraction and Mo ̈ssbauer spectra at room temperature. The lepidocrocite is paramagnetic at room temperature with a low field susceptibility of 57.8 108 m3 kg1. It undergoes magnetic ordering at low temperature and a peak in in-phase susceptibility occurs around 52 K, where it is antiferromagnetic. Thermal demagnetization of low-temperature remanence after cooling in zero field and in a 2.5-T field display a large loss in remanence from 5 to 30 K. Hysteresis loops are open and symmetric about the origin below 50 K; the remanent magnetization probably arises from a defect magnetic moment. The field-cooled hysteresis loop at 5 K is shifted along the field axis, which implies an exchange bias between antiferromagnetic and ferrimagnetic alignment in the lepidocrocite.
Low-Temperature magnetic properties of Lepidocrocite
LANCI, LUCA;
2002
Abstract
he magnetic properties of synthetic lepidocrocite (g-FeOOH) were investigated between 5 and 300 K. The purity of the samples was verified by X-ray diffraction and Mo ̈ssbauer spectra at room temperature. The lepidocrocite is paramagnetic at room temperature with a low field susceptibility of 57.8 108 m3 kg1. It undergoes magnetic ordering at low temperature and a peak in in-phase susceptibility occurs around 52 K, where it is antiferromagnetic. Thermal demagnetization of low-temperature remanence after cooling in zero field and in a 2.5-T field display a large loss in remanence from 5 to 30 K. Hysteresis loops are open and symmetric about the origin below 50 K; the remanent magnetization probably arises from a defect magnetic moment. The field-cooled hysteresis loop at 5 K is shifted along the field axis, which implies an exchange bias between antiferromagnetic and ferrimagnetic alignment in the lepidocrocite.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
