Quantum Monte Carlo simulation of antiferromagnetic spin ladder (C5H12N)2CuBr4

•Spin ladder antiferromagnetic compounds and low dimensional magnetism.•Quantum Monte Carlo simulation and the Heisenberg model.•Spin gap calculation, susceptibilitiy phase diagram and high magnetic fields.•Stochastic Series Expansion (SSE) method and low temperature magnetism.

In this paper I present a Quantum Monte Carlo (QMC) study of the magnetic properties of an antiferromagnetic spin ladder (C5H12N)2CuBr4. This compound is the prototype of the Heisenberg model for a two leg spin ladder in the presence of an external magnetic field. The susceptibility phase diagram has a rounded peak in the vicinity of T=7.4 K, obeys Troyer׳s law for low temperatures, and Curie׳s law for high temperatures. I also study the susceptibility diagram in low temperatures and I found the spin gap Δ=9.26 K, in good concordance with the experimental value, 9.5 K. In high field, I present a diagram of magnetization as a function of temperature. In the vicinity of a critical field, Hci, the magnetization scales with T1/2 and this result was found also in the QMC simulation. In all the results, there is a very good concordance with the experimental data. I also show in this paper that the spin gap is null and the susceptibility is proportional to T for low temperatures when relatively high values of the ladders’ coupling is taken in account.