A High Field Magnetic Study of the Spin Reorientations in Nd₆Fe₁₃Si


The field dependence of the magnetization in antiferromagnetic Nd6Fe13Si has been measured between 4.2 and 295 K under an applied magnetic field of between zero and 23 T. Isofield magnetization measurements at 1, 10, 15 and 20 T have also been carried out between 4.2 and 295 K. The magnetic phase diagram of Nd6Fe13Si contains three regions. between 4.2 and 110 K, the magnetic moments are aligned within the basal plane of the tetragonal unit cell and two critical fields are observed. between 160 and 295 K, the magnetic moments are aligned along the c-axis and one critical field is observed. Finally, between 110 and 160 K, a complex intermediate or mixed magnetic phase with up to three critical fields is observed. At 4.2 K and 23 T a hysteresis with a substantial coercive field of 0.4 T is observed. The presence of both two critical fields and hysteresis at low temperatures indicates a strong magnetic anisotropy within the basal plane. At 295 K an applied field of 23 T does not yield a complete spin flop of the axial magnetic moments, which remain canted. The critical field in the high temperature region is smaller than that observed in the low temperature region, indicating that the uniaxial antiferromagnetic exchange is weaker than the basal exchange. The temperature dependence of the magnetization under applied fields of 15 and 20 T shows the overall expected decrease with increasing temperature but with a break between 80 and 110 K in the spin reorientation region. Finally, the temperature dependence of the magnetization under applied fields of 10 T or less is very complex and results from a field induced canting of the magnetic moments below 30-40 K and a minimum in magnetic anisotropy around the spin reorientation at 110 K.




French National Center for Scientific Research
National Science Foundation (U.S.)

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