Four-spin cyclic exchange in spin ladder cuprates

Magnetic Phase Diagram of Spin-1/2 Two-Leg Ladder with Four-Spin Ring Exchange

We study the spin-1/2 two-leg Heisenberg ladder with four-spin ring exchanges under a magnetic field. We introduce an exact duality transformation which is an extension of the spin-chirality duality developed previously and yields a new self-dual surface in the parameter space. We then determine the magnetic phase diagram using the numerical approaches of the density-matrix renormalization-grou...

Quantum phase transition by cyclic four - spin exchange interaction for S = 1 / 2 two - leg spin ladder Yasushi Honda and Tsuyoshi Horiguchi

We investigate an S = 1/2 two-leg spin ladder with a cyclic four-spin exchange interaction whose interaction constant is denoted by J4, by using the density matrix renormalization group method. The interchain and the intrachain interaction constant are denoted by Jrung and Jleg, respectively and assumed to be antiferromagnetic. It turns out that a spin gap between the singlet (S tot = 0) and th...

Spin-ladder iron oxide: Sr3Fe2O5.

Spin-Fluctuation Mechanism of Superconductivity in Cuprates

Normal and superconducting state spectral properties of cuprates are theoretically described within the extended t-J model. The method is based on the equations of motion for projected fermionic operators and the mode-coupling approximation for the self-energy matrix. The dynamical spin susceptibility at various doping is considered as an input, extracted from experiments. The analysis shows th...

Signatures of Spin Dynamics in Cuprates

We show that a common feature of temperature-dependent microwave absorption is the presence of absorption peaks. ac loss peaks can arise when the internal T -dependent magnetic relaxation time crosses the measurement frequency. These features are observed in the insulating (SrxCa14−xCu24O41, La5/3Sr1/3NiO4 and Y Ba2Cu3O6.0), pseudo-gap (T > Tc in underdoped Y Ba2Cu3O7−δ , Hg : 1223 and Hg : 120...