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New Technique for Magnetic Phase Transitions Diagnostics

Tim G. Zagurenko 1Aleksei N. Lachinov 1Michael Matlak 2Victor M. Kornilov 1

1. Institute of Molecules and Crystal Physics, Ufa Scientific Centre of Russian Academy of Sciences, 151 Prospekt Oktyabrya, Ufa 450075, Russian Federation
2. University of Silesia, Katowice, Poland


It is commonly known that solids undergo phase transitions with changing temperature, characterized by a critical temperature. However the temperature behaviour of real solids is very often much more complicated. And here two main problems arise: how to detect mentioned characteristic temperatures and find out what really happens in solids at these temperatures.
This work presents a new technique for the diagnostic of the structural transformation in metals - the surface potential barrier method. The method is based on the measurement of the current flowing through the potential barrier formed on the metal - electroactive polymer interface. The current changes within the temperature range of the structural-phase transitions in metals may be big enough for their simple registration.
In present work Cr, Gd, GdCo2 samples demonstrating complex magnetic phase transitions were investigated.
The technique allowed both reproducing the well-known results with high certainty and obtaining a lot of complementary information about fine details of these transformations. For the Cr samples the Neel temperature (315 K), the fine structure of the antiferromagnetic-paramagnetic transition and the their dependence on the sample structure were detected. The measurements on the Gd sample revealed not only the Curie temperature (290 K), but also the characteristic temperature of the transition from a spiral to a ferromagnetic spin structure (~230 K). In case of the measurements on the GdCo2 sample the Curie (410 K) and characteristic temperatures associated with displacements of the Gd and Co ions and shift of the grain boundaries were detected.
Novel technique can be used to study fine structure of various structural transformations in metals and alloys, influence of external fields on the metals, etc. Earlier this method was employed successfully for the study of nanostructured materials.


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Related papers

Presentation: poster at E-MRS Fall Meeting 2003, Symposium B, by Tim G. Zagurenko
See On-line Journal of E-MRS Fall Meeting 2003

Submitted: 2003-05-08 07:03
Revised:   2009-06-08 12:55