Magnetothermopower ofδ-dopedLaTiO3/SrTiO3interfaces in the Kondo regime

Abstract

Measurements of magneto-thermopower (S(H, T)) of interfacial delta doped LaTiO3/SrTiO3 (LTO/STO) heterostructure by an iso-structural antiferromagnetic perovskite LaCrO3 are reported. The thermoelectric power of the pure LTO/STO interface at 300 K is ≈ 118 µV/K, but increases dramatically on δ-doping. The observed linear temperature dependence of S(T) over the temperature range 100 K to 300 K is in agreement with the theory of diffusion thermopower of a two-dimensional electron gas. The S(T) displays a distinct enhancement in the temperature range (T < 100 K) where the sheet resistance shows a Kondo-type minimum. We attributed this maximum in S(T) to Kondo scattering of conduction electron by localized impurity spins at the interface. The suppression of S by a magnetic field, and the isotropic nature of the suppression in out-of-plane and in-plane field geometries further strengthen the Kondo model based interpretation of S(H, T).

Magnetic Interactions at the Nanoscale in Trilayer Titanates

“…3(a), the other dominant feature in transport is the pronounced upturn of the sheet resistances at lower temperature. Previous work on titanate heterojunctions has attributed such an upturn to the Kondo effect [12,[63][64][65][66], after carefully ruling out the contributions from weak-localization [67] and electronelectron interactions [68]. One of the key features of the Kondo effect that immediately differentiates it from weak-localization and electron-electron interactions is the universal scaling behavior [see Fig.…”

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

“…The generation of 2DEG at the interface results in a metallic behaviour despite the insulating behaviour of bulk LTO and STO. Furthermore, at low temperatures LTO/STO heterostructure exhibits strong spin-orbit interaction (SOI) and Kondo scattering [15][16][17]. Along (0 0 1) direction, polar LTO lattice can be thought of as stacked alternating planes of (LaO) + and (TiO 2 ) − , whereas STO structure consists of neutral (SrO) 0 and (TiO 2 ) 0 planes.…”

Magnetic interactions at the nanoscale in trilayer titanates LaTiO$_3$/SrTiO$_3$/YTiO$_3$

“…3(a), the other dominant feature in transport is the pronounced upturn of the sheet resistances at lower temperature. Previous work on titanate heterojunctions has attributed such an upturn to the Kondo effect [12,[56][57][58][59], after carefully ruling out the contributions from weaklocalization [60] and electron-electron interactions [61]. One of the key features of the Kondo effect that immediately differentiates it from weak-localization and electron-electron interactions is the universal scaling behavior [see Fig.…”