Spin density in frustrated magnets under mechanical stress: Mn-based antiperovskites

In this paper we present results of first-principle calculations of the noncollinear spin density distribution in the systems with frustrated triangular magnetic structure [Mn-based antiperovskites, Mn3 AN (A=Ga,Zn)] in the ground state and under external mechanical biaxial strain. We show that the spin density in the (111)-plane of the unit cell is distinctly nonuniform. In particular, both the direction and the magnitude of spin density depend strongly on the distance from Mn site within atomic sphere. We show that the change of spin density under stress exhibits more diverse features than assumed in the rigid spin model. There are regions within atomic sphere where the spin density rotates in opposite directions under stress.