Projects per year
Abstract
Polarons and spinorbit (SO) coupling are distinct quantum effects that play a critical role in charge transport and spinorbitronics. Polarons originate from strong electronphonon interaction and are ubiquitous in polarizable materials featuring electron localization, in particular $\mathrm{3d}$ transition metal oxides (TMOs). On the other hand, the relativistic coupling between the spin and orbital angular momentum is notable in lattices with heavy atoms and develops in $\mathrm{5d}$ TMOs, where electrons are spatially delocalized. Here we combine ab initio calculations and magnetic measurements to show that these two seemingly mutually exclusive interactions are entangled in the electrondoped SOcoupled Mott insulator $\mathrm{Ba_2Na_{1x}Ca_xOsO_6}$ ($0< x < 1$), unveiling the formation of spinorbital bipolarons. Polaron charge trapping, favoured by the JahnTeller lattice activity, converts the Os $\mathrm{5d^1}$ spinorbital $\mathrm{J_{eff}=3/2}$ levels, characteristic of the parent compound $\mathrm{Ba_2NaOsO_6}$ (BNOO), into a bipolaron $\mathrm{5d^2}$ $\mathrm{J_{eff}=2}$ manifold, leading to the coexistence of different Jeffective states in a singlephase material. The gradual increase of bipolarons with increasing doping creates robust ingap states that prevents the transition to a metal phase even at ultrahigh doping, thus preserving the Mott gap across the entire doping range from $\mathrm{d^1}$ BNOO to $\mathrm{d^2}$ $\mathrm{Ba_2CaOsO_6}$ (BCOO).
Original language  English 

Article number  2429 
Number of pages  9 
Journal  Nature Communications 
Volume  15 
Early online date  27 Jun 2023 
DOIs  
Publication status  Published  18 Mar 2024 
Austrian Fields of Science 2012
 103009 Solid state physics
Keywords
 condmat.strel
Projects
 3 Active

Exchange Interactions in multicorrelated SpinOrbit Systems
Fiore Mosca, D.
1/12/22 → 30/11/25
Project: Research funding

TACO: Taming Complexity in Materials Modeling
Diebold, U., Kresse, G., MezgerBackus, E. H. G., Dellago, C. & Franchini, C.
1/03/21 → 28/02/25
Project: Research funding

Abinitio calculations for anharmonic polarons in hydrides
1/10/20 → 31/01/25
Project: Research funding