Ultrafast antiferromagnetic spin dynamics in high magnetic fields

This research explores how spins in magnetic materials behave when subjected to ultrafast laser pulses and high magnetic fields, with a focus on the phase diagram of ferri- and antiferromagnetic materials. The phase diagram is crucial in understanding the transitions between different magnetic states under varying temperature and magnetic field conditions. Femtosecond laser pulses rapidly heat materials like ferrimagnetic iron garnet and antiferromagnetic FeRh, driving them across critical points in their phase diagrams - such as the compensation temperature in iron garnet and the magnetostructural transition temperature in FeRh. These rapid temperature changes trigger ultrafast spin dynamics, which are analyzed in relation to the applied magnetic fields and temperatures.

The study reveals that spins in collinear phases of the materials are less responsive to laser-induced heating compared to those in non-collinear phases. The reorientation of spins towards equilibrium is delayed in collinear phases, taking longer due to the spin-lattice interaction.

The role of mechanical strain is also examined, showing how tensile or compressive strain influences the dynamics within the phase diagram. This research highlights how manipulating parameters like magnetic field, temperature, and strain can finely control phase transitions and spin behaviour for faster magnetic data processing.