Determination of exchange constants of Heusler compounds by Brillouin light scattering spectroscopy: application to Co₂MnSi

Brillouin light scattering spectroscopy from so-called standing spin waves in thin magnetic films is often used to determine the magnetic exchange constant. The data analysis of the experimentally determined spin-wave modes requires an unambiguous assignment to the correct spin wave mode orders. Often additional investigations are needed to guarantee correct assignment. This is particularly important in the case of Heusler compounds where values of the exchange constant vary substantially between different compounds. As a showcase, we report on the determination of the exchange constant (exchange stiffness constant) in Co$_2$MnSi, which is found to be $A=2.35\pm0.1$ $\mu$erg/cm ($D=575\pm20$ meV \AA$^2$), a value comparable to the value of the exchange constant of Co.