Kondo effect with tunable spin orbit interaction in LaTiO3/CeTiO3/SrTiO3 heterostructure

TL;DR

This study investigates the tunable spin-orbit interaction and Kondo effect in LaTiO3/CeTiO3/SrTiO3 heterostructures, revealing non-monotonic SOI behavior linked to interface screening and electronic subband population.

Contribution

It demonstrates how the spin-orbit interaction in heterostructures can be tuned via layer thickness, highlighting the role of interface screening and subband crossover in SOI modulation.

Findings

Maximum SOI field (B_SO) of 1.00 T at 6 u.c. CTO layer thickness.

Non-monotonic SOI behavior with layer thickness due to screening effects.

Orbital crossover from d_xy to d_xz_yz subbands enhances SOI.

Abstract

We have fabricated epitaxial films of CeTiO3 (CTO) on (001)oriented SrTiO3(STO) substrates, which exhibit highly insulating and diamagnetic properties. X-ray photoelectron spectroscopy (XPS) was to establish the 3+ valence state of the Ve and Ti ions. Furthermore, we also fabricated delta (CTO) doped LatiO3 (LTO)-STO thin films which exhibit variety of interesting properties including Kondo effect and spin orbit interaction (SOI) at low temperatures. SOI shows a non-monotonic behaviour as the thickness of the CTO layer is increased and is reflected in the value of the characteristic SOI field (B_SO) obtained from weak antilocalization fitting. The maximum value of B_SO is 1.00 T for delta layer thickness of 6 u.c. This non-monotonic behaviour of SOI is attributed to the strong screening of the confining potential at the interface. The thicker CTO film in addition to the increased dielectric constant of the STO substrate at low temperature leads to strong screening as a result of which the electrons confined at the interface are spread deeper into the STO bulk where it starts to populate the Ti d_xz_yz subbands; consequently the Fermi level crosses over from the d_xy to the d_xz_yz subbands. At the crossover region of d_xy - d_xz_yz where there is orbital mixing, SOI goes through a maximum.