Magnetic and electrical properties of Mn-doped p-type β-FeSi2 single crystals

Abstract

We investigated the temperature and magnetic field dependence of the Hall effect, the magnetization and the resistivity of Mn-doped β-FeSi2 single crystals in the temperature range of 4–300 K in magnetic fields up to 5 T. A negative magnetoresistance as well as strong nonlinear magnetic field dependence of the Hall resistivity and magnetization were observed. The anomalous contribution to the Hall resistivity is found to be important. We also observed the value of the anomalous Hall coefficient to increase with decreasing temperature as the square of the resistivity. It was shown that the magnetization of Mn-doped samples cooled in zero-external field and in a field are different. This resembles the properties of spin glasses. The dominant scattering mechanisms are determined by analyzing the Hall mobility data. The value of the valence band deformation potential is estimated. A particularly important role is played by the anomalous Hall effect which is the microscopic mechanism involving the spin dependent scattering on Mn ions and spin–orbit coupling in the Mn-doped β-FeSi2 single crystals.

Hopping conductivity in Mn-doped β-FeSi2 single crystals

“…24 Therefore, in conditions when N a is very close to N c whereas fluctuations of N a are comparable with the difference between N a and N c , the values of ␣ and should fluctuate too, which lead to the observed error of ϳ5% for ␣ and of ϳ15% for , the latter being higher due to the relation Ͼ , taking into account Eq. On the other hand, the real fluctuations of N a from sample to sample should be evidently higher than the difference of ϳ1% estimated above because they cannot be smaller than the error ϳ10% of the value of N a determined for sample L20.…”

Transport properties of β-FeSi2

“…36) However, the nonlinear field dependence of the Hall resistivity was reported also for the p-type Mn-doped β-FeSi 2 single crystals grown from high purity elements. 37) Manganese is one of the most effective doping elements for β-FeSi 2 used as a thermoelectric material. 33) Several studies were performed on polycrystalline alloys of β-Fe 1−x Mn x Si 2 with x = 0.01-0.1, and their transport properties were investigated at T = 77-1200 K. 34,35) The results of the transport measurements between T = 80 and 300 K were explained assuming the existence of the impurity band.…”

Effect of using a high-purity Fe source on the transport properties of p-type β-FeSi2 grown by molecular-beam epitaxy

“…Thus, we have to assume that the mobility is limited not only by acoustic phonon scattering but also by other scattering mechanisms. 24 The combined effect of the acoustic and nonpolar optical phonon scattering acnpo is given by…”

“…[22][23][24] Arushanov et al explained the temperature dependence of hole mobility of ␤-FeSi 2 grown by chemical vapor transport by using acoustic, nonpolar-optical, and polar-optical phonon scatterings. 23,24 On the other hand, there is a very limited number of reports that have investigated the transport properties of ␤-FeSi 2 films in detail. 25 Very recently, Ji et al described the formation of ␤-FeSi 2 films on Si͑111͒ by molecular-beam epitaxy ͑MBE͒ using a high-purity 5N-Fe source: 26 however, the electrical properties of these films were not discussed.…”