Theoretical investigation of excitonic magnetism in LaSrCoO4. (6th March 2018)

• Record Type: Journal Article
• Authors: Fernández Afonso, J; Sotnikov, A; Kuneš, J
• Is Part Of: Journal of physics. Volume 30:Number 13(2018)
• Publication Date: 2018-03-06
• Subjects: excitonic magnetism -- Co3+ -- linear spin-wave approximation; Condensed matter -- Periodicals; Matière condensée -- Périodiques; Vaste stoffen; Vloeistoffen; Natuurkunde; Electronic journals; Computer network resources; 530.4105
• DOI: 10.1088/1361-648X/aab0bb
• Languages: English
• ISSNs: 0953-8984

Abstract

Abstract: We use the LDA+U approach to search for possible ordered ground states of LaSrCoO4 . We find a staggered arrangement of magnetic multipoles to be stable over a broad range of Co 3 d interaction parameters. This ordered state can be described as a spin-density-wave-type condensate of d x y ⊗ d x 2 − y 2 excitons carrying spin S = 1. Further, we construct an effective strong-coupling model, calculate the exciton dispersion and investigate closing of the exciton gap, which marks the exciton condensation instability. Comparing the layered LaSrCoO4 with its pseudo cubic analog LaCoO3, we find that for the same interaction parameters the excitonic gap is smaller (possibly vanishing) in the layered cobaltite.