Influence of nickel on the electronic structure and magnetic properties in Gd₇Pd_3-xNi_x

Abstract

With increasing amount of nickel in the Gd₇Pd_3-xNi_x series, the unit cell volume decreases due to difference between atomic radius of Pd and Ni but the type of crystal structure is preserved. The paper presents X-ray diffraction, Scanning Electron Microscopy with Energy Dispersive X-ray Spectrometer, Transmission Electron Microscopy, AC and DC magnetic susceptibility and magnetocaloric examinations of the series. The Ni substitution into Pd position causes the decrease in the Curie temperature. Moreover, the dispersion observed in the AC-susceptibility at different frequencies vanishes at the Curie point. Just below the ordering temperature, a Hopkinson peak is observed. Complex processes depending on frequency and magnetic field occur in the transition region. The magnetization phenomena are very sensitive to the applied DC magnetic field and even very weak fields producing thermomagnetic hysteresis. A reorientation process around 150 K exists in all compounds and it is connected with increasing interactions at low temperatures. After nickel substitution, the relative cooling power (RCP) is greater in comparison to the parent compound.

Keywords:

• Rare-earth alloys and compounds
• crystal growth
• anisotropy
• magnetocaloric effect

Funding

This work was partially financed by the Polish National Science Centre (Narodowe Centrum Nauki) [grant number 2011/03/B/ST5/01035]. SQUID magnetometer was financed by European Regional Development Fund.