Articles written in Pramana – Journal of Physics
Volume 19 Issue 1 July 1982 pp 65-72 Instrumentation
A mutual inductance bridge to measure low frequency magnetic susceptibilities of magnetic materials has been constructed. Salient features of the bridge, which uses a variable mutual inductance simulated using operational amplifiers, the cryostat and the coil assembly are described in this paper. The apparatus has been employed for accurate measurement of superconducting transition temperatures and for sensitive detection of magnetic ordering transitions in liquid helium and liquid nitrogen temperature ranges respectively. The bridge has been calibrated to determine the static susceptibility of magnetic materials as a function of temperature.
Volume 33 Issue 4 October 1989 pp 513-519 Condensed Matter Physics
Detailed measurements of magnetization and ac susceptibility at low temperatures of 1% Zr-substituted Y9Co7 are presented. All results are indicative of itinerant weak ferromagnetism with
Volume 36 Issue 2 February 1991 pp 231-241
We report here both hardware and software for an ac susceptibility measurement system, namely the design and construction of the cryostat, coil system, sample rod assembly and also the automation of the sample rod movement, bridge control and nulling etc with the help of an inexpensive Z-80A microprocessor via a home-made IEEE-488 interface. The variable parameters are temperature, magnitude of the rms field and frequency. An entirely new dynamic bridge nulling algorithm with continuous sample movement, which eliminates to a large extent problems related to time-dependent drifts, has been developed. We also present some experimental data collected with this system.
Volume 38 Issue 6 June 1992 pp 695-702 Research Articles
We report the design and construction of a thermoelectric power apparatus using home-made electro-optic relays with Z-80A microprocessor for automatic data acquisition and control. The advantages of such relays made out of LED-LDR combinations for the measurement of Δ
Volume 58 Issue 5-6 May 2002 pp 995-1002 Colossal Magnetoresistance And Other Materials
Ferrites, combining insulating and ferrimagnetic properties, have long been used in technology. The aim of this paper is to focus on new features in these materials. In the classical theory of ferrimagnets, Néel had predicted the unusual thermal variation of the spontaneous magnetization, such as, the disappearance of the magnetization at a temperature which was not the Curie temperature but at a point where there was compensation of the spontaneous magnetization of the two sublattices. We show experimentally that temperature (
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