Structural and magnetic properties of YNi4-xCoxSi alloys
H. Gai (TU Delft - RST/Fundamental Aspects of Materials and Energy)
Niels Harmen H. Dijk (TU Delft - RST/Fundamental Aspects of Materials and Energy)
E. H. Brück (TU Delft - RST/Fundamental Aspects of Materials and Energy)
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Abstract
The transition-metal based alloy system YNi
4-xCo
xSi shows a second-order ferromagnetic-to-paramagnetic transition near room temperature. Here, the magnetic structure, the magnetocaloric properties and the magnetic anisotropy of YNi
4-xCo
xSi (x = 0–4) are investigated. For x = 3.5, 3.75 and 4.0 a Curie temperature near room temperature is observed with T
C = 250, 283 and 310 K, respectively. In orientated YNi
4-xCo
xSi powder samples the c axis of the hexagonal crystal structure is found to be the easy magnetic axis, with a large dominant K
2 anisotropy constant (K
2 > K
1 > 0). The magnetic structure and the preferred atomic position for Ni are demonstrated by neutron diffraction measurements. We have found a dramatic decrease in the magnetic moment at the 3 g site in the CaCu
5-type structure (space group P6/mmm), the saturation magnetization and the Curie temperature with increasing Ni concentration.
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