Dipolar interaction and exchange anisotropy in two-dimensional ferromagnetic quantum Heisenberg spin lattices.

Spin wave majority gates are considered as a viable beyond CMOS technology [1], if sufficiently scaled down. Although quantum effects are important when considering such scaled-down devices with thin ferromagnets, these are not sufficiently taken into account in today’s device simulations. Similarly, the effect of magnetic dipolar interaction on both the direction and magnitude of magnetization is poorly understood.

We present results [2] on the magnetization in two-dimensional ferromagnets with exchange anisotropy in an external magnetic field applied in an arbitrary direction. Using double-time temperature-dependent Green’s functions, we take into account quantum and thermal effects and we show the existence of a magnetic reorientation transition in anisotropic Heisenberg ferromagnets. Additionally, the framework can be extended to fully take into account magnetic dipole-dipole interaction, including its effect on the magnetization direction.

[1] I.P. Radu et al., Spintronic majority gates, IEEE IEDM (2015)
[2] J.Vanherck et al., Anisotropic bulk and planar Heisenberg ferromagnets in uniform, arbitrarily oriented magnetic fields, J. Phys. Condens. Matter (2018)