We address the effective tight-binding Hamiltonian that describes the insulating Mott state of
twisted graphene bilayers at a magic angle. In that configuration, twisted bilayers form a …

We calculate the thermodynamic quantities (correlation functions⟨ S 0 S n⟩, correlation
length ξ, spin susceptibility χ, and specific heat CV) of the frustrated one-dimensional spin …

We use the rotation-invariant Green's function method (RGM) and the high-temperature
expansion to study the thermodynamic properties of the Heisenberg antiferromagnet on the …

The thermodynamic properties (magnetization, magnetic susceptibility, transverse and
longitudinal correlation lengths, and specific heat) of one-and two-dimensional ferromagnets …

We present a spin-rotation-invariant Green-function theory of long-and short-range order in
the ferro-and antiferromagnetic Heisenberg model with arbitrary spin quantum number S on …

Using the spin-rotation-invariant Green's-function method, we calculate the thermodynamic
quantities (correlation functions⟨ S 0 SR⟩, uniform static spin susceptibility χ, correlation …

We use the spin-rotation-invariant Green's function method as well as the high-temperature
expansion to discuss the thermodynamic properties of the frustrated spin-SJ 1-J 2 …

We apply the rotation-invariant Green's function method to study the finite-temperature
properties of a S= 1/2 sawtooth-chain (also called Δ-chain) antiferromagnetic Heisenberg …

We use a second-order rotational invariant Green's-function method (RGM) and the high-
temperature expansion (HTE) to calculate the thermodynamic properties of the kagome …

The two-time Green's function method is used to study the critical properties and crossover
phenomena near the field-induced quantum critical point (QCP) of ad-dimensional spin-S …