Feasibility of a metamagnetic transition in correlated systems

The long-standing issue of the competition between the magnetic field and the Kondo effect, favoring, respectively, triplet and singlet ground states is addressed using a cluster slave-rotor mean field theory for the Hubbard model and its spin-correlated, spin-frustrated extensions in 2 dimension. The metamagnetic jump is established and compared with earlier results of dynamical mean-field theory. The present approach also reproduces the emergent super-exchange energy scale in the insulating side. A scaling is found for the critical Zeeman field in terms of the intrinsic coherence scale just below the metal-insulator transition where the critical spin fluctuations are soft. The conditions for metamagnetism to appear at a reasonable field are also underlined. The Gutzwiller analysis on the 2D Hubbard model and a quantum Monte Carlo calculation on the Heisenberg spin system are performed to check the limiting cases of the cluster slave-rotor results for the Hubbard model. Low-field scaling features for magnetization are discussed.

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