PhD Mid-term Seminar Series: Nonlinear transport effects in chiral elemental Tellurium

CIC nanoGUNE Seminars

Manuel Suárez-Rodríguez
Pre-doctoral researchers, Nanodevices group, nanoGUNE
nanoGUNE seminar room, Tolosa Hiribidea 76, Donostia - San Sebastian
Add to calendar
Subscribe to Newsletter
PhD Mid-term Seminar Series: Nonlinear transport effects in chiral elemental Tellurium

Chiral materials are an ideal playground for exploring the relation between symmetry, relativistic effects, and electronic transport [1]. Indeed, the role of low symmetry on electronic transport has been studied on chiral organic molecules, but their poor electronic conductivity limits their potential for applications. Conversely, chiral inorganic crystals, such as elemental Tellurium (Te), present excellent electrical conductivity and strong spin-orbit coupling [2]. Therefore, Te become a perfect material for studying the connection between nonlinear transport phenomena, such as unidirectional magnetoresistance (UMR) [3] or nonlinear Hall effect (NLHE) [4], and chirality. Here, we synthesized single crystalline Te nanowires (NWs) and flakes with both handedness. On one hand, we report a chirality-dependent and gate-tuneable Edelstein effect in the naturally hole-doped Te NWs [5]. By recording a UMR dependent on the relative orientation of the electrical current and the external applied magnetic field, we link the direction of the spin polarization to the handedness of the crystal. The measured UMR is explained on the basis of a chirality-dependent Edelstein effect arising from the radial spin texture at the H-point of the valence band of Te, which dominates the transport in our hole-doped Te NWs. In addition, an electrostatic gating enables the tuning of the Edelstein effect, leading to a modulation of the UMR amplitude by a factor of 6. On the other hand, we explore the NLHE in Te flakes. The symmetry of the measured second harmonic voltage under zero field, which is a consequence of the inversion symmetry breaking in Te, follows strictly the constrains for Te point group and is different from any material reported before. Moreover, by measuring flakes with opposite handedness, we were able to explore experimentally the effect of an inversion symmetry operation [6]. The all-electrical generation, control, and detection of spin polarization and second-order voltage in chiral Te NWs open the path to exploit chirality in the design of solid-state spintronic and energy harvesting devices.

[1] S.-H. Yang et al. Nat. Rev. Phys.3, 328–343 (2021).
[2] M. Sakano et al. Phys. Rev. Lett.124, 136404 (2020).
[3] A. Dyrdał et al. Phys. Rev. Lett.124, 046802 (2020).
[4] Z. Z. Du et al. Nat. Rev. Phys.3, 744–752 (2021).
[5] F. Calavalle†, M. Suárez-Rodríguez†et al. Nat. Mater.21, 526-532 (2022).
[6] M. Suárez-Rodríguez et al. Submitted (2023).