Impact of magnetic anisotropy on the magnon Hanle effect in $\alpha$-Fe${}_2$O${}_3$

Abstract

In easy-plane antiferromagnets, the nature of the elementary excitations of the spin system is captured by the precession of the magnon pseudospin around its equilibrium pseudofield, manifesting itself in the magnon Hanle effect. Here, we investigate the impact of growth-induced changes in the magnetic anisotropy on this effect in the antiferromagnetic insulator $\alpha$-Fe${}_2$O${}_3$ (hematite). To this end, we compare the structural, magnetic, and magnon-based spin transport properties of $\alpha$-Fe${}_2$O${}_3$ films with different thicknesses grown by pulsed laser deposition in molecular and atomic oxygen atmospheres. While in films grown with molecular oxygen a spin-reorientation transition (Morin transition) is absent down to $10$K, we observe a Morin transition for those grown by atomic-oxygen-assisted deposition, indicating a change in magnetic anisotropy. Interestingly, even for a $19$nm thin $\alpha$-Fe${}_2$O${}_3$ film grown with atomic oxygen we still detect a Morin transition at $125$K. We characterize the magnon Hanle effect in these $\alpha$-Fe${}_2$O${}_3$ films via all-electrical magnon transport measurements. The films grown with atomic oxygen show a markedly different magnon spin signal from those grown in molecular oxygen atmospheres. Most importantly, the maximum magnon Hanle signal is significantly enhanced and the Hanle peak is shifted to lower magnetic field values for films grown with atomic oxygen. These observations suggest a change of magnetic anisotropy for $\alpha$-Fe${}_2$O${}_3$ films fabricated by atomic-oxygen-assisted deposition resulting in an increased oxygen content in these films. Our findings provide new insights into the possibility to fine-tune the magnetic anisotropy in $\alpha$-Fe${}_2$O${}_3$ and thereby to engineer the magnon Hanle effect.

References in corpus (12)

• Direct electronic measurement of the spin Hall effect
• Subterahertz spin pumping from an insulating antiferromagnet
• Magnon Mediated Electric Current Drag Across a Ferromagnetic Insulator Layer
• Temperature dependence of the magnon spin diffusion length and magnon spin conductivity in the magnetic insulator yttrium iron garnet
• Observation of Antiferromagnetic Magnon Pseudospin Dynamics and the Hanle effect
• Spin Currents and Magnon Dynamics in Insulating Magnets
• Spin Hall magnetoresistance in antiferromagnetic insulators
• Antiferromagnetic magnon pseudospin: Dynamics and diffusive transport
• Observation of nonreciprocal magnon Hanle effect
• Antiferromagnetic resonance in $\alpha$-Fe${}_2$O${}_3$ up to its Néel temperature
• Role of substrate clamping on anisotropy and domain structure in the canted antiferromagnet $\alpha$-Fe${}_2$O${}_3$
• All-electrical Magnon Transport Experiments in Magnetically Ordered Insulators

Cited by in corpus (2)

• Anisotropic Field Suppression of Morin Transition Temperature in Epitaxially Grown Hematite Thin Films
• Coherent Spin Pumping Originated from Sub-Terahertz Néel Vector Dynamics in Easy Plane α-Fe2O3/Pt