Structural and magnetic phase transitions in CoxNi1−xMnGe system under pressure |
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| Authors: | S. Nizioł A. Ziȩba R. Zach M. Baj L. Dmowski |
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| Affiliation: | Institute of Physics and Nuclear Techniques, University of Mining and Metallurgy, Cracow, Poland;Institute of Physics, Technical University of Cracow, Cracow, Poland;Institute of Physics, Warsaw University, Warsaw, Poland;High Pressure Research and Development Center UNIPRESS, Polish Academy of Sciences, Warsaw, Poland |
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| Abstract: | The interaction of magnetic (Tc) an first-order distortion-type structural (TD) transitions in the CoxNi1?xMnGe system was investigated using an ac susceptibility method under hydrostatic pressure up to 1.3 GPa. For all compositions TC increases and TD decreases with pressure. At the first triple point (0.3–0.6 GPa depending on x) these transitions go through a simultaneous magnetic-structural transition, as observed by Anzai and Ozawa in NiMnGe. However, for the composition x = 5, at the second triple point (at 0.8 GPa) the magnetic transition separates from the structural one, with TC greater than TD. This appears to be the first example of physically different, first and second-order phase transitions merging at a particular value of an external parameter, i.e. pressure PTR1 and decoupling again at PTR2 > PT1. The (P, T) phase diagrams and the nature of the triple points are discussed using a simple Landau-type theory |
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