Articles written in Pramana – Journal of Physics
Volume 1 Issue 2 August 1973 pp 61-65 Geophysics
Studies on two rare cases of magnetic behaviour in basaltic rocks are reported. In both the cases a peak in susceptibility occurs at −160°C. However, one sample shows only normal hysteresis loops at low temperatures in a wide range of fields, while the other sample shows a constricted hysteresis loop in 1000 Oe at −190°C. Both types of behaviour can occur as a result of differing states of aggregation of interacting superparamagnetic particles in the respective samples.
Volume 13 Issue 4 October 1979 pp 413-422 Solids
It is shown that hysteresis and susceptibility studies at various temperatures could provide an idea whether a magnetic sample contains multidomain, single-domain or superparamagnetic particles. Our results on titanomagnetites with those of others on cobalt substituted magnesium ferrites suggest that domain wall formation is inhibited in some of them whereby only single-domain or superparamagnetic particles occur irrespective of the physical grain size of such materials. At high concentration of titanium in titanomagnetites, the magnetic behaviour is similar to a spin glass, which we interpret as a transition of optimum single-domains going over to superparamagnetic state.
Volume 30 Issue 2 February 1988 pp 1- Rapid Communications
We have studied the hysteresis loops of RBa2Cu3O7 (R=Gd, Ho and Y) and detected anomalies in some of them. The observed anomalies support a recent prediction by Ravi Kumar and Chaddah based on an extension of Bean’s model. The anomalies indicate low
Volume 30 Issue 6 June 1988 pp 569-595 Condensed Matter Physics
We present DC and low frequency AC magnetization measurements on various RBa2Cu3O7 superconductors. We identify features intrinsic to these compounds, and establish the features originating from intergranular links in sintered pellets. The isothermal magnetization curves, and the temperature dependence of magnetization in field-cooled and zero field-cooled states are shown to be consistent with the calculations done following a recent extension of Bean’s model. Low field anomalies predicted within this model are observed, and yield
Volume 35 Issue 4 October 1990 pp 377-381
The temperature dependence of magnetic susceptibility,
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