Magnetism in Rare-Earth-Transition Metal Systems. Magnetization Reversal and Ultra-High Susceptibility in Sandwiched Thin Films Based on Rare-earth and Cobalt Alloys

Abstract

This paper is composed of two parts: theoretical and experimental. The theoretical part is divided into several sections. The main characteristic properties of 3d (transition metals) and 4f (rare-earth metals) magnetism are explained in the second section. The properties of rare-earth-transition metal compounds are discussed in the third section, particularly with respect to applications. The fourth section is devoted to the rapidly growing field of magnetic thin films. Specifrc properties of ultra-thin films and multilayers are summarized. In the experimental part the original magnetic properties of sandwich films, consisting of a soft amorphous Co-Zr layer placed between two Sm-Co layers with different coercivities, are reported.

Magnetic moment orientation and in depth distribution of dysprosium near the surface of DyCo$_{4.6}$ thin films determined by the analysis of their X ray circularly polarized absorption Dy $M_{5}$ spectra

“…The different T Comp measured in these alloys using TEY and bulk detection [5], together with the reported RE segregation at their surface [17,18], has been used as an argument to explain interesting phenomena that occurs at temperatures near their T Comp when the applied magnetic field is intense enough. The hysteresis loops of some DyCo alloys of similar concentration than the samples used in this study presented side wing loops at high applied fields as the presented in some spring magnet-like bilayer structures [3,4,19]. The effect was explained as derived from the effective different RE concentration at the bulk and the region near the surface which will yield two different T Comp for each region [5,20].…”

Magnetic moment orientation and in-depth distribution of dysprosium near the surface of DyCo4.6 thin films from x-ray circularly polarized absorption

“…The different T comp measured in these alloys using TEY and bulk detection [5], together with the reported RE segregation at their surface [17,18], has been used as an argument to explain interesting phenomena that occur at temperatures near their T comp when the applied magnetic field is intense enough. The hysteresis loops of some DyCo alloys of similar concentration than the samples used in this study presented side wing loops at high applied fields as presented in some spring magnetlike bilayer structures [3,4,19]. The effect was explained as derived from the effective different RE concentrations at the bulk and the region near the surface, which will yield two different T comp for each region [5,20].…”

Observation of Anomalously High Seebeck Coefficients in the Family of Zintl Phase Semiconductors Ca10RECdSb9 (RE = Rare-Earth Metal)

“…An example of a typical role-play of a magnetic specie in thermoelectric performance enhancement is found in the magnetism-mediated thermoelectric properties of the Cr-doped Bi 2 Te 3 phase and MnBi. − However, while the magnetism of transition metals from Cr to Ni due to electrons in the 3d electronic shells is stable at temperatures much higher than room temperature, the temperatures of magnetic ordering in rare-earth metals (Ce to Yb) due to unfilled 4f electronic shells are generally much lower than room temperature and the magnetic interactions between the moments are much weaker in comparison to those of transition metals. In addition, the 3d orbital occupies the outer shells as against the inner shell occupied by the 4f orbital, and as such, the 3d electrons can actively contribute to the electronic band structure more than the 4f electrons . It, therefore, suffices to reason that the local magnetic moment of the 4f electrons in these phases is not likely to have a significant impact on the observed high-temperature transport properties.…”

“…In addition, the 3d orbital occupies the outer shells as against the inner shell occupied by the 4f orbital, and as such, the 3d electrons can actively contribute to the electronic band structure more than the 4f electrons. 46 It, therefore, suffices to reason that the local magnetic moment of the 4f electrons in these phases is not likely to have a significant impact on the observed hightemperature transport properties. At best, such an effect would be more significant at low temperatures where the magnetic interactions of the magnetic ions become more pronounced.…”