Nanocomposites and nanomaterials

The structure magnetic properties of  microwires with the low Curie temperature
Delov V.V.1, Kutseva N.A.1, Kushnerov O.I 1, Bashev V.F. 1 , Larin V.S.2
1 Department of Experimental and Metal Physics ,Oles Honchar Dnipro National University, Gagarin Ave, 72, Dnipro-49010, Ukraine.
E-mail: delovse@gmail.com
2 MicroFir Tehnologii Industriale, str. Gurie Grosu 26, ap. 39 Chisinau, R. Moldova 

    Amorphous glass-coated Co-Fe-Si-B magnetic microwires (MW)  with nearly zero magnetostriction are attractive for applications in modern microelectronics an nanoelectronics. They combine the excellent magnetic properties, magneto-transport properties (Giant magneto-impedance (GMI) effect, Giant Magneto-resistance (GMR) effect) with small size and cheap production. Additions of Ni and Cr lead to significant decreasing of the Curie temperature, that can be used in temperature sensors. 
Initial MW of nominal composition Co43,3Fe20Cr8B11Si12,7C3Mo2 (metallic nucleus diameter 61 μm and coating thickness 55 μm) was obtained by the Taylor-Ulitovski technique. X-ray analysis showed, that initial MW has amorphous structure. The coherent scattering region determined from  the integral width of intensity peak was approx. 4 nm. This structure determined magnetic properties :coercivity 40 A/m; Br/Bs=0,9.      
The Curie temperature (TC) was evaluated from  the temperature dependence of curves of magnetization. It was found that TC of MW was approx. 110 oC. The annealing of MW at the temperature 115 oC lead to the increasing of the  coherent scattering region to 5 nm.
As well known, amorphous structure is inhomogeneous and consist of the clusters with different short order. It is probable that in the structure of MW there are two magnetic phases and one of them with low Curie temperature.