Effect of Magnetic (Nd) Doping on Electrical and Magnetic Properties of Topological Sb2Te3 Single Crystal

Here, we report the growth and characterization of single crystals of NdxSb2-xTe3 (x = 0 and 0.1), by solid-state reaction route via self-flux method. The phase and layered growth are confirmed through X-ray diffraction and scanning electron microscopy respectively. A slight contraction in lattice parameters is seen after Nd doping. Also a minute shift in vibrational modes of recorded Raman spectra has been observed by doping of Nd in Sb2Te3. The magneto-resistance values under magnetic field of 5 Tesla for Sb2Te3 are 75% at 2.5 K and 60% at 20 K, but only 40% at 5 K for Nd0.1Sb1.9Te3. DC magnetic measurements exhibit expected diamagnetic and paramagnetic behaviors for pure and Nd doped crystals respectively. A cusp-like behavior is observed in magneto-conductivity of both pure and Nd doped crystals at low magnetic fields (< 1 Tesla) which is analyzed using Hikami-Larkin-Nagaoka (HLN) model. For Sb2Te3, the fitted parameters alpha are -1.02 and -0.58 and the phase coherence lengths L-phi are 50.8(6)nm and 34.9(8)nm at temperatures 2.5 and 20 K respectively. For Nd0.1Sb1.9Te3, alpha is -0.29 and L-phi is 27.2(1)nm at 5 K. The alpha values clearly show the presence of weak anti-localization effect in both pure and Nd doped samples. Also with Nd doping, the contribution of bulk states increases in addition to conducting surface states in overall conduction mechanism.