We study the effects of electron doping in Mott insulators containing d^4 ions such as Ru4+, Os4+, Rh5+, and Ir5+ with J=0 singlet ground state. Depending on the strength of the spin-orbit coupling, the undoped systems are either nonmagnetic or host an unusual, excitonic magnetism arising from a condensation of the excited J=1 triplet states of t_2g^4. We find that the interaction between J-excitons and doped carriers strongly supports ferromagnetism, converting both the nonmagnetic and antiferromagnetic phases of the parent insulator into a ferromagnetic metal, and further to a nonmagnetic metal. Close to the ferromagnetic phase, the low-energy spin response is dominated by intense paramagnon excitations that may act as mediators of a triplet pairing.
@article{arxiv.1510.07508,
title = {Doping-Induced Ferromagnetism and Possible Triplet Pairing in d4 Mott Insulators},
author = {Jiří Chaloupka and Giniyat Khaliullin},
journal= {arXiv preprint arXiv:1510.07508},
year = {2016}
}
Comments
5 pages, 4 figures; minor refinements, published version