Light‐Induced Giant Rashba Spin–Orbit Coupling at Superconducting KTaO₃(110) Heterointerfaces

Abstract

The 2D electron system (2DES) at the KTaO 3 surface or heterointerface with 5d orbitals hosts extraordinary physical properties, including a stronger Rashba spin-orbit coupling (RSOC), higher superconducting transition temperature, and potential of topological superconductivity. Herein, a huge enhancement of RSOC under light illumination achieved at a superconducting amorphous-Hf 0.5 Zr 0.5 O 2 /KTaO 3 (110) heterointerface is reported. The superconducting transition is observed with T c = 0.62 K and the temperature-dependent upper critical field reveals the interaction between spin-orbit scattering and superconductivity. A strong RSOC with B so = 1.9 T is revealed by weak antilocalization in the normal state, which undergoes sevenfold enhancement under light illumination. Furthermore, RSOC strength develops a dome-shaped dependence of carrier density with the maximum of B so = 12.6 T achieved near the Lifshitz transition point n c ≈ 4.1 × 10 13 cm −2 . The highly tunable giant RSOC at KTaO 3 (110)-based superconducting interfaces show great potential for spintronics.

钽酸钾界面超导的发现与研究进展

“…AlO x [33] 、TiO x [34] 、YAlO 3 [35] 、LaVO 3 [36] 、La 2/3 Sr 1/3 -MnO 3 [37] 、LaTiO 3 [18] 、Hf 0.5 Zr 0.5 O 2 [38]…”

“…1 [39] 低至25 mK不超导 [15] EuO 外延 1.35(onset), 门电压可调至 1.7 [31] LAO 非晶 2 [27] 0.9 [16] 低至25 mK不超导 [15] AlO x 非晶 1.7 [33] TiO x 非晶 1.1 [34] YAlO 3 非晶 1.86 [35] LSAT* 非晶 2 Hf 0.5 Zr 0.5 O 2 非晶 0.62 [38] LaVO 3 外延 0.5 [36] 低至50 mK不超导 [36] 低至50 mK不超导 [36] LaTiO 3 外延 1.4 [18] 0.9 [18] 低至40 mK不超导 [18] La 2/3 Sr 1/3 MnO 3 外延 1.5 [37] CaHfO 3 * 外延 0.6…”

“…除了上述两种调控手段之外, 光照 [38,62] 、电子 束 [55] 、离子液体门电压调控 [40,63] 等也可以有效调控 KTO界面导电及超导. 此外, 通过调整生长参数, 可以 在很大程度上调控KTO界面的性质 [64] .…”

Light-induced giant enhancement of nonreciprocal transport at KTaO3-based interfaces

“…As a 5 d transition-metal oxide, KTaO 3 (KTO)-based interfaces hosting 2DEGs have aroused considerable interest owing to fascinating physical properties, such as 2D anisotropic superconductivity 31 – 34 , tunable strong Rashba SOC 35 – 39 , and robust spin polarization 40 . Especially, the superconductivity at KTO-based interfaces is strongly dependent on the crystalline orientation of KTO with the highest superconducting transition temperature ( T C ) of 2.2 K at (111)-oriented surface 31 , very different from SrTiO 3 -based counterparts, indicating the underlying rich physics in KTO.…”