Europhys. Lett., 62 (5) , pp. 732-738 (2003)
Presence of a paramagnetic phase well below the ferromagnetic onset in 0.67-x xJ. R. Sun1, B. G. Shen1, J. Gao2, Y. Fei3 and Y. P. Nie4
1 State Key Laboratory for Magnetism, Institute of Physics and Center for Condensed Matter Physics, Chinese Academy of Sciences - Beijing 10080, PRC
2 Department of Physics, the Hong Kong University - Pokfulam Road, Hong Kong, PRC
3 Australian Nuclear Science and Technology Organization, Lucas Heights, Laboratories Menai 2234, Australia
4 Department of Physics, Sichuan University - Chengdu 19904, PRC
(Received 21 January 2003; accepted in final form 4 April 2003)
Partial replacement of by in depresses the ferromagnetic order of the compound and leads to a stepwise magnetic behavior characterized by two subsequent transitions at and . Based on a combined study of the electron spin resonance spectra and the thermal and isothermal magnetization, a complete scenario for the phase separation that causes the complex behavior has been given. It is found that the paramagnetic phase exists in a wide temperature region even below the ferromagnetic onset at . It coexists with the ferromagnetic phase below and with both the ferromagnetic and antiferromagnetic phases below with a reduced but significant fraction. The magnetization jump at is possibly a conversion of the remaining paramagnetic phase into the ferromagnetic phase.
75.50.Dd - Nonmetallic ferromagnetic materials.
76.30.-v - Electron paramagnetic resonance and relaxation.
75.30.Vn - Colossal magnetoresistance.
© EDP Sciences 2003