title: Rashba coupling amplification by a staggered crystal field.
abstract: 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 eV Å, leading to a remarkable band splitting up to 0.15 eV with hidden spin-chiral polarization in centrosymmetric BaNiS2. This is explained by a huge staggered crystal field of 1.4 V Å(-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.
authors.affiliation: IMPMC, Sorbonne Universités, Université Pierre et Marie Curie, CNRS, IRD, MNHN, 4 place Jussieu, 75252 Paris, France.
authors.forename: David
authors.initials: D
authors.lastname: Santos-Cottin
authors.affiliation: IMPMC, Sorbonne Universités, Université Pierre et Marie Curie, CNRS, IRD, MNHN, 4 place Jussieu, 75252 Paris, France.
authors.forename: Michele
authors.initials: M
authors.lastname: Casula
authors.affiliation: Laboratoire de Physique des Solides, CNRS, Université Paris-Sud, Université Paris-Saclay, 91405 Orsay, France.
authors.forename: Gabriel
authors.initials: G
authors.lastname: Lantz
authors.affiliation: IMPMC, Sorbonne Universités, Université Pierre et Marie Curie, CNRS, IRD, MNHN, 4 place Jussieu, 75252 Paris, France.
authors.forename: Yannick
authors.initials: Y
authors.lastname: Klein
authors.affiliation: Elettra Sincrotrone Trieste, Strada Statale 14 km 163.5, 34149 Trieste, Italy.
authors.forename: Luca
authors.initials: L
authors.lastname: Petaccia
authors.affiliation: Synchrotron SOLEIL, L'Orme des Merisiers, BP 48 Saint-Aubin, 91192 Gif-sur-Yvette Cedex, France.
authors.forename: Patrick
authors.initials: P
authors.lastname: Le Fèvre
authors.affiliation: Synchrotron SOLEIL, L'Orme des Merisiers, BP 48 Saint-Aubin, 91192 Gif-sur-Yvette Cedex, France.
authors.forename: François
authors.initials: F
authors.lastname: Bertran
authors.affiliation: Laboratoire de Physique des Solides, CNRS, Université Paris-Sud, Université Paris-Saclay, 91405 Orsay, France.
authors.forename: Evangelos
authors.initials: E
authors.lastname: Papalazarou
authors.affiliation: Laboratoire de Physique des Solides, CNRS, Université Paris-Sud, Université Paris-Saclay, 91405 Orsay, France.
authors.forename: Marino
authors.initials: M
authors.lastname: Marsi
authors.affiliation: IMPMC, Sorbonne Universités, Université Pierre et Marie Curie, CNRS, IRD, MNHN, 4 place Jussieu, 75252 Paris, France.
authors.forename: Andrea
authors.initials: A
authors.lastname: Gauzzi