Nonreciprocal Transport in a Rashba Ferromagnet, Delafossite PdCoO₂

Abstract

Rashba interfaces yield efficient spin-charge interconversion and give rise to nonreciprocal transport phenomena. Here, we report magnetotransport experiments in few-nanometer-thick films of PdCoO 2 , a delafossite oxide known to display a large Rashba splitting and surface ferromagnetism. By analyzing the angle dependence of the firstand second-harmonic longitudinal and transverse resistivities, we identify a Rashba-driven unidirectional magnetoresistance that competes with the anomalous Nernst effect below the Curie point. We estimate a Rashba coefficient of 0.75 ± 0.3 eV Å and argue that our results qualify delafossites as a new family of oxides for nanospintronics and spin− orbitronics, beyond perovskite materials.

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

“…1 ) and has been widely discovered in other noncentrosymmetric systems 23 , 24 . Meantime, the R / R 0 undergoes a gradual saturation with increasing field, which is likely attributed to the complex effect of the large Zeeman energy exerting on the band structures 52 , 53 . Moreover, the nonreciprocal transport gradually weakens with increasing temperature and vanishes at around 40 K, which is attributed to the disruption of spin-momentum locking by quantum fluctuations (Supplementary Fig.…”

A large unidirectional magnetoresistance in Fe–Sn heterostructure devices

“…1(b). This magnetothermal EMF gives rise to the same dependences of the signal on H f and j with the USMR, 18,22,23) requiring further measurement to distinguish the dominant origin. Under application of the ac current, I = I 0 sin t w , the temperature gradient due to the Joule heating is given by…”

“…Furthermore, the normalized amplitude of the UMR R UMR /R 0 /j monotonically increases by a factor of 27 from 3.0 ´10 −16 to 8.2 × 10 −15 m 2 A −1 when the Fe-Sn thickness increases from 4 to 100 nm, which supports the proposed scenario that the magnetothermal origin dominates the remaining two-thirds of UMR in the Fe-Sn heterostructure devices. Further improvement of the R UMR /R 0 /j can be anticipated by properly designing heterointerfaces by modulating the interfacial Rashba spin-orbit interaction 15,16,23) or electron-magnon scattering and magnon excitation, 19,20,24,25) which accelerates the optimization of the sensing properties of the 3D magnetic sensor based on Fe-Sn and topological magnets.…”

“…The origins of the UMR in ferromagnetic heterostructures have been discussed in spin-dependent scattering [13][14][15][16][17][18][19][20][21] and the magnetothermal effect. 18,22,23) The former is referred to as unidirectional spin Hall magnetoresistance (USMR), as schematically shown in Fig. 1(a), which is composed of bulk [12][13][14] and interface contributions.…”

Anisotropic linear and nonlinear charge-spin conversion in topological semimetal SrIrO3

“…Under a small perturbation, such as an external electric eld, both distribution and eigenstate in a carrier system are modi ed, giving rise to different nonequilibrium distributions and thereby the spin currents. Besides the linear response regime, recently, high-order response of charge-spin conversion to electric eld has been theoretically proposed and also experimentally observed in noncentrosysmetric transition metal dichalcogenides, topological Dirac semimetals, and two-dimensional Rashba-Dresselhaus systems [15][16][17][18][19][20][21][22][23][24][25][26][27][28][29][30]. The high-order response is closely related to nontrivial spin textures and topology due to strong SOC with inversion symmetry broken, resulting in a variety of quantum phenomena, such as nonlinear planar/anomalous Hall, nonreciprocal nonlinear optical and inverse Edelstein effects.…”