Dresden 2020 – wissenschaftliches Programm

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TT: Fachverband Tiefe Temperaturen

TT 5: Frustrated Magnets - General 1 (joint session TT/MA)

TT 5.2: Vortrag

Montag, 16. März 2020, 09:45–10:00, HSZ 304

Microscopic meaning of the Goodenough-Kanamori-Anderson (GKA) rule in frustrated cuprates — •Stefan-Ludwig Drechsler1, Liviu Hozoi1, Ravi Yadav1, Satoshi Nishimoto1,2, Rolf Schumann2, Jan M. Tomczak3, Dijana Miloslavlevic4, and Helge Rosner41IFW-Dresden, D-01171 Dresden Germany — 2TU Dresden, Germany — 3Vienna University of Technology, Vienna, Austria — 4MPI-cPfS, Dresden, Germany

Within the multiband (pd) Hubbard model we consider the influence of the ferromagnetic (fm) intersite exchange Kpd and that of the intra-site Hund’s rule exchange JH on bridging O in between two Cu-sites on the NN exchange J1 within a spin-model for cuprates with edge-sharing elements. Based on quantum chemistry (QC), DFT, GW, and exact calculations for small clusters and extended systems we determine the main interactions and transfer integrals for several representative cuprates with edge-sharing elements. In most such compounds with Cu-O-Cu bond angles near 90o the relatively large −J1 > 230 K is dominated by a nonuniversal Kpd > 100 meV, i.e. significantly larger than 50 meV adopted previously /1/. In contrast to common belief, JH < 0.8 eV is moderate and somewhat screened. It plays only a minor role in the GKA. Moderate JH-values are in accord with results for superoxides /2/. Enlarged Kpd∼ 200 meV agree with QC for corner-sharing cuprates /3/ and empirically with CuGeO3 (∼ 100 meV) /2/.

[1] Y. Mizuno et al., Phys. Rev. B 57, 5326 (1998).

[12] M. Matsuda et al., ibid. 100 104415 (2019) and references therein.

[3] M.S. Hybertsen et al., ibid. 45, 10032 (1992).

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