Nanoscale physics 

Spin-orbit interaction in InSb core-shell wires
Druzhinin A., Ostrovskii  I., Khoverko Yu., Liakh-Kaguy N., 
Lukianchenko A. 

Lviv Polytechnic National University. St.Bandera Str.,12, Lviv-79013, Ukraine. 
E-mail: anton290398@gmail.com

Semiconductor systems of zinc-blende type posse strong spin-orbit interaction (SOI) resulting in Rashba and Dresselhaus contributions to magnetoresistance. The SOI induced by bulk inversion asymmetry is named after Dresselhaus. Rashba SOI results from the electric field due to asymmetry of the confining potential on the surface, interface, i.e. in quantum well. Recently [1], the negative MR of InSb films was found to crossover to the positive MR in weak magnetic fields with decreasing the film thickness from d = 1 µm to 0.1 µm. The effect has been explained by transition from the weak localization (WL) caused by SO scattering rate in the intrinsic InSb film due to the bulk inversion asymmetry (Dresselhaus term) to the weak antilocalization (WAL) with the increase of SOI in the layers caused by the increased influence of the Rashba electric field when the interface is approached in the film. Measurement of the spin splitting of the lowest Landau level by scanning tunnelling spectroscopy allowed to obtain the local electrostatic potential for an InSb inversion layer with a large Rashba coefficient (1 eV Å).  On the other hand, theoretical analysis of weak antilocalization carried out in [1] enabled to obtain a large Rashba spin-orbit strength of 0.5–1 eV °A corresponding to a spin-orbit energy of 0.25–1 meV in InSb nanowires. It is worthy to note, that Dresselhaus term in SOI can be neglected along the axis of nanowire.  Thus, Rashba contribution to SOI is under the consideration. The next point to be taken into account is core-shell wire structure, which introduced additional increase of Rashba SOI due to an increase of the structural inversion asymmetry. Moreover, the cross-sectional distribution of impurities in the nanowire is important for conductance channel mapping.
The aim of present paper is to study Rashba spin-orbit interaction in Sn doped InSb core-shell wires by investigation of their magnetoresistance at low temperatures 2-10 K at magnetic field induction up to 2 T. Crossover from WAL to WL was observed in the wires at decrease of doping concentration from  1017 cm-3  to 6 1016 cm-3. The possible reasons of the observed effects are discussed. 

1.	Van Weperen I.,  Tarasinski B., Eeltink D., Pribiag V. S.,, Plissard S. R., Bakkers E. P. A. M., Kouwenhoven L. P., and Wimmer M.  Spin-orbit interaction in InSb nanowires // Physical Review B. – 2015.– Vol. 91. –  P.201413.