Abstract
We report on the comprehensive experimental and theoretical studies of magnetic and electronic structural properties of the Gd0.4Tb0.6Co2 compound crystallization in the cubic Laves phase (C15). We present new results and compare them to those reported earlier. The magnetic study was completed with electronic structure investigations. Based on magnetic isotherms, magnetic entropy change (ΔSM) was determined for many values of the magnetic field change (Δμ0H), which varied from 0.1 to 7 T. In each case, the ΔSM had a maximum around room temperature. The analysis of Arrott plots supplemented by a study of temperature dependency of Landau coefficients revealed that the compound undergoes a magnetic phase transition of the second type. From the M(T) dependency, the exchange integrals between rare-earth R-R (JRR), R-Co (JRCo), and Co-Co (JCoCo) atoms were evaluated within the mean-field theory approach. The electronic structure was determined using the X-ray photoelectron spectroscopy (XPS) method as well as by calculations using the density functional theory (DFT) based Full Potential Linearized Augmented Plane Waves (FP-LAPW) method. The comparison of results of ab initio calculations with the experimental data indicates that near TC the XPS spectrum collects excitations of electrons from Co3d states with different values of exchange splitting. The values of the magnetic moment on Co atoms determined from magnetic measurements, estimated from the XPS spectra, and results from ab initio calculations are quantitatively consistent.
Highlights
IntroductionMagnetic properties of Laves phase compounds have recently been of great interest to researchers [1,2,3,4]
Magnetic properties of Laves phase compounds have recently been of great interest to researchers [1,2,3,4].A relatively simple crystal structure, facilitating the interpretation of the investigation results, was the main reason for this
That the magnetic phase transition for this compound is near room temperature
Summary
Magnetic properties of Laves phase compounds have recently been of great interest to researchers [1,2,3,4]. A relatively simple crystal structure, facilitating the interpretation of the investigation results, was the main reason for this In this family of materials, special attention should be paid to Laves phases containing rare-earth (R) and transition metal (T) atoms. They are interesting because of additional interactions between magnetic moments (4f’-4f, 4f-3d, 4f’-3d, and others) which may significantly alter the magnetic properties of the original material and strongly modify their electronic structure. Using the two-sublattice model, in the mean-field theory (MFT) approximation, the exchange integrals JRR , JRCo , and JCoCo were evaluated Within this theory, we determined the magnetic moment of Co atoms μCo-MFT and compared it with ts values obtained by other methods
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