Magnetic Properties of the Hubbard Model on Kagome Stripes

O. Derzhkoa,b, M. Maksymenko a, J. Richter c, A. Honecker d and R. Moessner b aInstitute for Condensed Matter Physics, NAS of Ukraine, 1 Svientsitskii Str., L'viv-11, 79011, Ukraine bMax-Planck-Institut für Physik Komplexer Systeme, Nöthnitzer Str. 38, 01187 Dresden, Germany cInstitut für Theoretische Physik, Universität Magdeburg, P.O. Box 4120, 39016 Magdeburg, Germany dInstitut für Theoretische Physik, Georg-August-Universität, F.-Hund-Pl. 1, 37077 Göttingen, Germany

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We consider the one-orbital N-site repulsive Hubbard model on two kagome like chains, both of which yield a completely dispersionless (flat) one-electron band. Using exact many-electron ground states in the subspaces with n ≤ nmax (nmax ∝ N) electrons, we calculate the square of the total spin in the ground state to discuss magnetic properties of the models. We have found that although for n < nmax the ground states contain fully polarized states, there is no finite region of electron densities n/N < 1 (N = N/3 or N = N/5) where ground-state ferromagnetism survives for N → ∞.

DOI: 10.12693/APhysPolA.118.736 PACS numbers: 71.10.-w