Impurity Ferromagnetism of Pd-Fe and Pd-Co Alloys: Ab Initio vs. Experiment

We have performed full-stack research of Pd_1-xFe_x and Pd_1-xCo_x (x = 0.01-0.1) alloys. At the first stage, the occurrence of impurity ferromagnetism in considered alloys was studied employing the Density Functional Theory (DFT). Calculations revealed that considered impurities can initialize significant magnetization of the Pd atoms, in particular, the maximum magnetization for the Pd_1-xFe_x system was found to be ~8μ_B at x = 0.07, whereas Co produces a much higher magnetization for the Pd_1-xCo_x alloy which is equal to ~15 μ_B at x = 0.02, where μ_B is a Bohr magneton. We also found that the induced magnetization depends on the position of the impurities in the host matrix. The calculations showed that the maximum magnetization is observed with a uniform distribution of the dissolved impurity.

At the second stage, magnetic impurities of Fe and Co atoms were implanted into epitaxial Pd thin films to verify DFT results. The concentration of impurities in the Pd matrix was adjusted by the dose of implantation. Magnetic properties of implanted Pd films were investigated by Vibrating Sample Magnetometer (VSM) in the temperature range from 5K to 300K. The VSM data were recalculated to get the value of the magnetic moment in terms of Bohr magnetons per implanted magnetic ion of impurity.

It has been established that VSM results are in good agreement with ab initio calculations. It was shown that the value of the magnetic moments of the Pd films implanted with Fe⁺ (or Co⁺) ions are close to the calculated values for corresponding concentrations.

This work was supported by the RFBR Grant No. 20-02-00981.