Study On The Properties Of High Positive Mr Of AB₂ Type Metal Compound RuSb_2+?and Mn-doped RuSb_2+?

Magresistor is widely used in magnetic random access memory,magnetic valve,magnetic sensor,magnetic switch and other devices.Physical quantities such as displacement,angle and velocity can be measured more accurately by magnetoresistance effect.Recently,AB₂-type compounds have attracted a lot of attention due to a series of fascinating properties,such as topological insulating,superconducting,and huge magnetoresistance.In nonmagnetic single crystals,MR is closely related to the changed electronic density of state by the applied magnetic field.For this subject,the magnetoresistance changes and band gap properties of RuSb_2+?single crystals were studied,and the band structure of RuSb_2+?was speculated.The electric transport and magnetoelectric properties of Mn doped RuSb_2+?were studied.The main research results of this paper are as follows:RuSb_2+?single crystals grown by the self-flux method form rhombic structure with space group Pnnm.A high positive magnetoresistance,78%,is observed at 2K on the ab plane of the diamagnetic RuSb_2+?semiconductor.On the ac plane,MR is44%at 2K and about 7% at 300 K.The quantum interference effect with the weak localization correction lies behind the high positive MR at low temperature.MR at different temperatures do not follow the Kohler's rule.It suggests that the multiband effect plays a role on the carrier transportation.The Seebeck factor is positive at 300K,and it decreases with the temperature and becomes negative below 60 K.RuSb_2+?is a semiconductor with both positive and negative carriers.Judged from the UV-Vis and XPS,it has a direct band gap of 1.29eV.The valence band is 0.39eV below the Fermi energy.The schematic energy band structure is proposed based on experimental results.The d electron of Ru atom has t_2gstate and e_gstate,and the t_2gstate is lower than the e_gstate.t_2gis separated from the valence band to form a band gap.Ru_1-xMn_xSb_2+?(x=0,0.05,0.08)single crystals grown by the self-flux method form rhombic structure with space group Pnnm.The effect of cell volume reduction in the presence of Mn doping is much greater than that of excess Sb.The resistivity of Mn doping is much smaller than that of undoping and decreases as x increases.In addition,the peak resistivity disappears,showing a metallic nature.In addition,the peak resistivity disappeared and showed metallic properties.Mn doping changes the electronic structure of Ru_1-xMn_xSb_2+?.For Mn doped RuSb_2+?,Sb splitting effectively improves the hole concentration,reduces the resistivity and leads to a small band splitting,indicating multi-band electrical conduction.When Mn is doping,the electron concentration increases obviously with the increase of x.Mn is thought to contribute the same(so-called equivalent doping)or fewer electrons than Ru⁴⁺.The increase of electron concentration is probably the result of Mn doping changing the band structure.The transverse MR Of Ru_0.92Mn_0.08Sb_2+?can be as high as 78%at 2K and 14T on the ab place.It can be considered that Mn doped RuSb_2+?can produce high positive MR Materials with good thermoelectric properties.