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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 Nishimoto^1,2, Rolf Schumann², Jan M. Tomczak³, Dijana Miloslavlevic⁴, and Helge Rosner⁴ — ¹IFW-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 K_pd and that of the intra-site Hund’s rule exchange J_H 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 90^o the relatively large −J₁ > 230 K is dominated by a nonuniversal K_pd > 100 meV, i.e. significantly larger than 50 meV adopted previously /1/. In contrast to common belief, J_H < 0.8 eV is moderate and somewhat screened. It plays only a minor role in the GKA. Moderate J_H-values are in accord with results for superoxides /2/. Enlarged K_pd∼ 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).