Electron scattering processes in Ho5(SixGe

Abstract

We present a detailed study of the temperature dependence of the electrical resistivity [ρ(T )] in the range 13-300 K for the Ho 5 (Si x Ge 1−x ) 4 system. Three distinct ρ(T ) behaviors are observed, associated with different magnetic and crystallographic structures along the series. In the samples with an antiferromagnetic phase (AFM) one observes a shoulder near the Néel temperature (T N ) attributed to the formation of a gap on the Fermi surface. This gap is analyzed using a phenomenological two-band model for an AFM with distinct atomic and magnetic periodicities, and its effect seems to extend well above T N . We also found the presence of short-range magnetic clusters in the paramagnetic (PM) phase. On the ferromagnetic (FM) materials, the distinct ρ(T ) scattering contributions (phonon, magnetic, and residual terms) are extracted from the measurements, with ρ(T ) mainly dominated by electron spin scattering. An additional contribution is also observed, arising from the strong crystal field effect in these materials. The effect is mainly observed in the PM phase, leading to a curvature on ρ(T ) in this phase. Using a two-level crystal field model the corresponding gap was estimated for the different Si/Ge ratio samples, revealing that the crystal field splitting increases linearly with Si content.

Electronic, magnetic, and transport properties of the isotypic aluminides SmT2Al10(T= Fe, Ru)

“…The onset of the ordered state in ρ(T ) of SmFe 2 Al 10 is equally evident in the electron density probe measurement of Hall resistivity ρ xy (T ) (figure 5(c)). We follow the approach of Pereira et al [68] and the earlier work of Elliott and Wedgewood [69] whereby the leading temperature dependence of effects of superzone boundaries in ρ(T ) below an AFM transition is given by;…”

Effect of Tb substitution in naturally layered LaMn2Si2: magnetic, magnetocaloric, magnetoresistance and neutron diffraction study

“…Since the discovery of giant MR in La based manganites [37], considerable attention has been devoted to the study of MR behaviour of other materials exhibiting similar behaviour. Also, the materials having layered structure exhibit interesting magneto-transport behaviour [38][39][40]. Although extensive amount of work has been carried out in studying the magnetic properties of these Mn based 1:2:2 compounds, there exist very few reports of magneto-transport behaviour [41].…”

Tailoring the magnetism of Tb5Si2Ge2compounds by La substitution

“…31 Such results indicate the presence of different local interactions that can decrease the effective magnetic moment, such as crystal field effects as recently found in the Ho system. 34 From the extrapolation of the high-temperature regime (T > 200 K), using the Curie Weiss law, the paramagnetic Curie temperature ( P ) is extracted. Neutron diffraction measurements were performed in order to obtain new information of simultaneously magnetic and atomic structure as a function of temperature, enabling the representation of neutron thermodiffractograms, which are shown in Fig.…”