Magnetic properties of Cu3.9Fe3.4V6O24 with a lyonsite structure

• Dc magnetization and EPR measurements were used to study Cu3.9Fe3.4V6O24.
• Magnetic moment in paramagnetic phase was smaller than expected.
• Transition to AFM phase was observed in weak external magnetic fields.
• Magnetic clusters and dimers are formed due to crystallographic structure.

Magnetic properties of the lyonsite-type phase, Cu3.9Fe3.4V6O24, that has been synthesized by a standard solid-state reaction method, were investigated by dc magnetization and electron paramagnetic resonance (EPR) techniques. Complex magnetic behavior and transition to the antiferromagnetic phase at liquid helium temperature have been revealed by measurements of dc susceptibility in ZFC and FC modes in the 2–300 K temperature range as well as static magnetization in magnetic fields up to 70 kOe. Strong antiferromagnetic interactions in clusters or chains of magnetic ions even at high temperatures has been deduced from the obtained value of the effective magnetic moment that was significantly smaller than expected for nominal valences of iron and copper ions. The presence of antiferromagnetic iron dimers in the high-temperature range, critical slowing down of spin fluctuations on approaching Neel temperature and the existence of magnetically isolated iron ions in the antiferromagnetic phase has been suggested from the temperature dependence of EPR parameters (g-factor, linewidth, integrated intensity) obtained by fitting the experimental spectrum with Lorentzian lineshape.

Figure optionsDownload as PowerPoint slide