Rashba coupling amplification by a staggered crystal field

David Santos-Cottin (1) , Michele Casula (1) , Gabriel Lantz (2) , Yannick Klein (1) , Luca Petaccia (3) , Patrick Le Fèvre (4) , François Bertran (4) , Evangelos Papalazarou (2) , Marino Marsi (2) , Andrea Gauzzi (1)

1 IMPMC - Institut de minéralogie, de physique des matériaux et de cosmochimie
2 LPS - Laboratoire de Physique des Solides
3 Elettra Sincrotrone Trieste
4 SSOLEIL - Synchrotron SOLEIL

There has been increasing interest in materials where relativistic effects induce non-trivial electronic states with promise for spintronics applications. One example is the splitting of bands with opposite spin chirality produced by the Rashba spin-orbit coupling in asymmetric potentials. Sizable splittings have been hitherto obtained using either heavy elements, where this coupling is intrinsically strong, or large surface electric fields. Here by means of angular resolved photoemission spectroscopy and first-principles calculations, we give evidence of a large Rashba coupling of 0.25 eVÅ, leading to a remarkable band splitting up to 0.15 eV with hidden spin-chiral polarization in centrosymmetric BaNiS 2. This is explained by a huge staggered crystal field of 1.4 VÅ À 1 , produced by a gliding plane symmetry, that breaks inversion symmetry at the Ni site. This unexpected result in the absence of heavy elements demonstrates an effective mechanism of Rashba coupling amplification that may foster spin-orbit band engineering.

Domaines: Physique [physics]

David Santos-Cottin, Michele Casula, Gabriel Lantz, Yannick Klein, Luca Petaccia, et al.. Rashba coupling amplification by a staggered crystal field. Nature Communications, 2016, 7, pp.11258. ⟨10.1038/ncomms11258⟩. ⟨hal-01320032⟩