Some recent stories about conducting oxide interfaces: Nontrivial electronic band structure, nontrivial spin texture in real and momentum space.

In recent times, momentum dependent splitting of spin-bands in an electronic system, the “Rashba effect”, has gained a lot of interest because of its applications in future generation spintronic devices.[1,2] The Rashba effect is important not only because it has tremendous potential for technical applications, but also because it is a hunting ground for emergent physical properties owing to the linear dispersion relation at the crossing point of the two spin bands.[3] In this work, we present the observation of emergent phenomena arising at the interface of two insulating perovskite oxides due to Rashba spin-band splitting. In our first work, we improvise a novel conducting interface by juxtaposing KTaO3 (KTO) with another insulator, namely LaVO3 (LVO).[4] This heterointerface exhibits strong spin-orbit coupling which is the highest among perovskite oxide heterostructures reported so far. The system is also found to show the signature of topological chiral anomaly via observation of planar Hall effect (PHE) and anomalous in-plane magnetoresistance (AMR) similar to that observed for topological systems. [5] In addition, surprising quantum oscillations have been observed in magneto-resistance. A nonlinear dependence of Landau index as a function of the inverse of applied magnetic field has been observed.

In our next work, we show the realization of a spin polarized optically transparent interface. The quest for realizing highly spin-polarized conduction in materials at room temperature is one of the central themes of material physics. We report the realization of a conducting interface of two insulating perovskite oxides namely LaFeO3 (LFO) and SrTiO3 (STO) that demonstrates the signatures of spin-polarization, namely negative magnetoresistance, and anomalous Hall resistivity above 150 K and even up to the room temperature. However, the same system shows positive magnetoresistance and normal Hall effect at temperatures below 150 K. The origin of this could be understood phenomenologically as magnetic proximity and a topological effect of Berry’s phase originating from the nonlinear spin arrangement in the system due to thermal fluctuations at high temperatures. In addition, this interface appears to be almost transparent in the entire range of visible light. Our observation is not only of interest to fundamental science but is also viewed as a step towards “room-temperature transparent oxide-spintronics.”

Our works could be found in

Advanced Electronic Materials 2200195 (2022).
Advanced Materials 34 (9), 2106481 (2022).
Adv. Quantum Technol. 2100105 (2022).
Phys. Rev. B (Lett.) 104, L081111 (2021).
Adv. Quantum Technol. 2000081 (2020).
Advanced Materials Interfaces, 000: 2000646 (2020).
Nature communication, 11: 874(1-7) (2020).
Applied Surface Science, 509: 145214 (2020).
Advanced Material Interfaces, 1900941(1-6) (2019).
Physical Review B 96 (11), 115423 (2017).
 

References:

[1] S. Datta, and B. Das, Appl. Phys. Lett., 56, 665 (1990).

[2] Y.A. Bychkov, and E.I. Rashba, JETP Lett. 39, 78 (1984).

[3]H. Murakawa, M.S. Bahramy, M. Tokunaga, Y. Kohama, C. Bell, Y. Kaneko, N. Nagaosa, H. Hwang, and Y. Tokura, Science 342, 1490 (2013).

[4] N. Wadehra, R. Tomar, R.K. Gopal, Y. Singh, S. Dattagupta, and S. Chakraverty, Nature Communication, 1,
874 (2020).

[5] A.A. Taskin, H.F. Legg, F. Yang, S. Sasaki, Y. Kanai, K. Matsumoto, A. Rosch, and Y. Ando, Nat.
Commun. 8, 1340-1 (2017).

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