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In order to derive tensorial exchange interactions and local magnetic anisotropies in itinerant magnetic systems, an approach combining the Spin-Cluster Expansion with the Relativistic Disordered Local Moment scheme is introduced. The theoretical background and computational aspects of the method are described in detail. The exchange interactions and site resolved anisotropy contributions for the IrMn3/Co(111) interface, a prototype for an exchange bias system, are calculated including a large number of magnetic sites from both the antiferromagnet and ferromagnet. Our calculations reveal that the coupling between the two subsystems is fairly limited to the vicinity of the interface. The magnetic anisotropy of the interface system is discussed, including effects of the Dzyaloshinskii-Moriya interactions that appear due to symmetry breaking at the interface.
Motivated by recent experiments on the Heisenberg S=1/2 quantum spin liquid candidate material kapellasite, we classify all possible chiral (time-reversal symmetry breaking) spin liquids with fermionic spinons on the kagome lattice. We obtain the pha
We give a complete classification of fully symmetric as well as chiral $mathbb{Z}_2$ quantum spin liquids on the pyrochlore lattice using a projective symmetry group analysis of Schwinger boson mean-field states. We find 50 independent ansatze, inclu
We employ the cluster slave-spin method to investigate systematically the ground state properties of the Hubbard model on a square lattice with doping $delta$ and coupling strength $U$ being its parameters. In addition to a crossover reflected in the
Quantum spin liquids (QSL) have generated considerable excitement as phases of matter with emergent gauge structures and fractionalized excitations. In this context, phase transitions out of QSLs have been widely discussed as Higgs transitions from d
We present a multiloop pseudofermion functional renormalization group (pffRG) approach to quantum spin systems. As a test case, we study the spin-$tfrac{1}{2}$ Heisenberg model on the kagome lattice, a prime example of a geometrically frustrated magn