Articles written in Pramana – Journal of Physics
Volume 10 Issue 5 May 1978 pp 453-465 Solids
A scheme to calculate the electron momentum density in simple liquid metals, with the effect of
Volume 28 Issue 5 May 1987 pp 547-553
Some of the recent work on disorder-induced changes in
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 31 Issue 4 October 1988 pp 1- Rapid Communications
We have measured the transport critical current density
Volume 31 Issue 6 December 1988 pp 505-512 Condensed Matter Physics
We present a calculation of the isothermal magnetization hysteresis curves appropriate to high
Volume 33 Issue 2 August 1989 pp 297-313 Condensed Matter Physics
The existence of a remanent magnetization (
Volume 33 Issue 4 October 1989 pp 521-540 Condensed Matter Physics
We present exact solutions of Bean’s critical state model for some sample shapes having non-zero demagnetization factor
Volume 34 Issue 4 April 1990 pp 279-287
We have studied the variation of low field magnetization hysteresis in YBa2Cu3O7 as a function of the maximum magnetic field applied during a hysteresis cycle (1 G<
Volume 36 Issue 4 April 1991 pp 353-392 Review
Magnetic measurements in the superconducting state of the high temperature superconductors have been characterized by the feature of irreversibility. Similar effects have been known in the conventional type II superconductors for about three decades now, and have been studied in great detail during the last few years. Recent studies of magnetic irreversibilities, in both conventional and high temperature superconductors, will be reviewed here. Thermally-activated relaxation accompanies such irreversibilities, and studies on flux-creep will also be reviewed.
This review shall cover the measurement of isothermal magnetization curves, of ac susceptibility, of thermo-magnetic history effects in the magnetization at a particular field and temperature, and of flux creep. An understanding of these in terms of Bean’s celebrated macroscopic model shall be discussed. We shall also cover measurements that confirm the existence of weak links in ceramic high-temperature, as well as in conventional multifilamentary, superconductors.
Volume 37 Issue 6 December 1991 pp 525-538 Research Articles
A comparison has been made of irreversibility temperature determined by four different methods in few specimens of lead (type-I) and niobium (type-II). The merger of
Volume 41 Issue 1 July 1993 pp 51-60
We present measurements of harmonic generation in the magnetization of sintered pellets of YBa2Cu3O7 and Bi1.7Pb0.3Sr2Ca2Cu3O10 as a function of DC field. The DC field is applied in the field-cooled mode. Measurements are made at 77 K for various values of the AC field amplitude. A comparison is made with calculations done within the critical state model.
Volume 45 Issue 3 September 1995 pp 261-269
Results are presented for study of nonlinear magnetization of a sintered YBa2Cu3O7−y pellet of different thickness of a sample subjected to very low magnetic field. On cooling the sample below
Volume 53 Issue 4 October 1999 pp 659-684 Review Article
Superconductivity in CeRu2 was discovered 40 years ago, and was extensively studied because alloying with magnetic elements showed the coexistence of superconductivity and magnetic order. The normal state of CeRu2 has been of interest because of its intermediate valuence character. The superconducting state has been studied extensively because of its paramagnetic nature and anomalous pinning properties. This review presents the present status of knowledge, and discusses the puzzling features of CeRu2.
Volume 54 Issue 6 June 2000 pp 857-862
Hysteresis in cycling through first-order phase transitions in vortex matter, akin to the well-studied phenomenon of supercooling of water, has been discussed in literature. Hysteresis can be seen while varying either temperature
Volume 56 Issue 5 May 2001 pp 657-665 Research Articles
We present a model in which metastable supercooled phase and stable equilibrium phase of vortex matter coexist in different regions of a sample. Minor hysteresis loops are calculated with the simple assumption of the two phases of vortex matter having field-independent critical current densities. We use our earlier published ideas that the free energy barrier separating the metastable and stable phases reduces as the magnetic induction moves farther from the first order phase transition line, and that metastable to stable transformations occur in local regions of the sample when the local energy dissipation exceeds a critical value. Previously reported anomalous features in minor hysteresis loops are reproduced, and calculated field profiles are presented.
Volume 67 Issue 1 July 2006 pp 113-119
We shall discuss magnetization and transport measurements in materials exhibiting a broad first-order transition. The phase transitions would be caused by varying magnetic field as well as temperature, and we concentrate on ferro- to antiferromagnetic transitions in magnetic materials. We distinguish between metastable supercooled phases and metastable glassy phase.
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