En las fronteras de la Materia Condensada

We have studied the magnetic properties of the natural noncollinear multilayered system LaMn₂Ge₂. This system shows a magnetic state with the Mn atoms ordered in a conical arrangement (spin spiral) with a ferromagnetic coupling along the c-axis below 322 K. On the other hand the measured giant magnetoresistance (GMR) is inverse and increases linearly with the magnetic field, making this system a very exciting one to study the influence of noncollinearity on transport properties. The magnetic structure was studied by performing ab initio calculations within the LDA approximation, based on FP-LAPW method. We found a spin spiral magnetic ground state with the magnetic moment of the Mn atoms being of about 3µ_B. The optimum canting angle was about 60° and the optimun q_z value of the spin spiral was around 0.6389 (2/c), while the experimental values are 58° and 0.7389 (2/c), respectively.