From weak antilocalization to Kondo scattering in a magnetic complex oxide interface

Abstract

Quantum corrections to electrical resistance can serve as sensitive probes of the magnetic landscape of a material. For example, interference between time-reversed electron paths gives rise to weak localization effects, which can provide information about the coupling between spins and orbital motion, while the Kondo effect is sensitive to the presence of spin impurities. Here we use low-temperature magnetotransport measurements to reveal a transition from weak antilocalization (WAL) to Kondo scattering in the quasi-two-dimensional electron gas formed at the interface between SrTiO 3 and the Mott insulator NdTiO 3 . This transition occurs as the thickness of the NdTiO 3 layer is increased. Analysis of the Kondo scattering and WAL points to the presence of atomic-scale magnetic impurities coexisting with extended magnetic regions that affect transport via a strong magnetic exchange interaction. This leads to distinct magnetoresistance behaviors that can serve as a sensitive probe of magnetic properties in two dimensions.

Carrier‐Modulated Anomalous Electron Transport in Electrolyte‐Gated SrTiO3

“…Before checking whether the Kondo physics works here, it is necessary to exclude other possible mechanisms for the R s (T ) upturn below T m . It is known that weak localization (WL) effect may also cause the resistance upturn, [35] which was indeed observed in the STO surficial layer with other chemical treatments [36] and also in our case when the carrier density is close to the MIT threshold. [25] Nevertheless, the measured R xx (H)/R xx (0) curve at T = 2 K, as shown in Figure 3c, exhibits clear cusps as H !…”

Two-dimensional electron gas at the (001) surface of ferromagnetic EuTiO3

“…In particular, DFT + U calculations show that the exchange interaction between Ti-3d states and ordered Eu 2+ magnetic moments in the lattice is essential to create a spin-polarized q2DEG. We anticipate that other systems where a spin-polarized 2DEGs could be realized are GdTiO 3 [34] and NdTiO 3 [35], which are the magnetic counterpart of the 3d 1…”

Robust Weak Antilocalization Effect Up to ∼120 K in the van der Waals Crystal Fe5–xGeTe2 with Near-Room-Temperature Ferromagnetism

“…As a quantum correction to the classical conductivity, the weak antilocalization (WAL) effect can originate from either the strong spin−orbit coupling (SOC) in the bulk materials or spin momentum locking in the topological surface states of topological phases, 8,9 such as in Bi−Se−Te−Sb topological insulators, 10−14 Dirac semimetals with either weak (e.g., graphene) or strong SOC, 15,16 atomic-scale metal films, 17 two-dimensional (2D) transitional metal dichalcogenides (TMDs), 18−21 etc. However, there have been very few reports of the WAL effect in magnetic systems, 22,23 and the WAL effect has not been observed in vdW ferromagnet nanoflakes remains to the best of our knowledge. In insulating vdW ferromagnets, the ferromagnetism can be described well by an anisotropic Heisenberg model in which local moments correlate with each other via FM interactions, 24,25 while in vdW FM metals such as Fe 3 GeTe 2 , the electronic itinerancy should be interpreted by using other models.…”