Effect of magnetic (Nd) doping on electrical and magnetic properties of topological Sb2Te3 single crystal

TL;DR

This study investigates how Nd doping affects the structural, magnetic, and electrical properties of Sb2Te3 single crystals, revealing changes in lattice parameters, vibrational modes, magneto-resistance, and conduction mechanisms.

Contribution

It provides new insights into the effects of Nd doping on topological Sb2Te3, including structural modifications and enhanced bulk conduction contributions.

Findings

Nd doping causes lattice contraction and vibrational mode shifts.

Magneto-resistance decreases with Nd doping, especially at low temperatures.

Weak anti-localization persists in both pure and doped samples.

Abstract

Here, we report the growth and characterization of single crystals of NdxSb2-xTe3, 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 5Tesla for Sb2Te3 are 75 percent at 2.5K and 60 percent at 20K, but only 40 percent at 5K 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 below 1 Tesla which is analyzed using Hikami Larkin Nagaoka (HLN) model. For Sb2Te3 the fitted parameters alpha values are -1.02 and -0.58 and the phase coherence lengths are 50.8(6)nm & 34.9(8)nm at temperatures 2.5K and 20K respectively. For Nd0.1Sb1.9Te3, alpha is -0.29 and coherence length is 27.2(1) nm at 5K. 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.