Possible 2-order magnetic phase transition in the Gd1-xYx systemA. Vl. Andrianov and O. A. Savelieva
Department of Physics, Moscow State University - Moscow 119991, Russia
received 22 November 2007; accepted in final form 31 March 2008; published May 2008
published online 16 May 2008
The magnetic phase transition "helical antiferromagnet-ferromagnet" in the Gd0.66Y0.34 and Gd0.65Y0.35 samples was examined by means of the specific heat, resistivity and magnetic susceptibility vs. temperature. The characteristic anomaly on the temperature dependence of the specific heat suggests that this phase transition in both the samples is not a second-order phase transition as might be expected, but a so-called second-and-a-halforder phase transition. The phenomenon is due to the change in the Fermi surface topology with temperature that is also responsible for the change in the magnetic structure.
75.25.+z - Spin arrangements in magnetically ordered materials (including neutron and spin-polarized electron studies, synchrotron-source, X-ray scattering, etc.).
75.30.Kz - Magnetic phase boundaries (including magnetic transitions, metamagnetism, etc.).
71.18.+y - Fermi surface: calculations and measurements: effective mass, g factor.
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