Exchange-Striction Driven Ultrafast Nonthermal Lattice Dynamics in NiO

We use femtosecond electron diffraction to study ultrafast lattice dynamics in the highly correlated antiferromagnetic (AFM) semiconductor NiO. Using the scattering vector (Q) dependence of Bragg diffraction, we introduce Q-resolved effective temperatures describing the transient lattice. We identify a nonthermal lattice state with preferential displacement of O compared to Ni ions, which occurs within similar to 0.3 ps and persists for 25 ps. We associate this with transient changes to the AFM exchange strictioninduced lattice distortion, supported by the observation of a transient Q asymmetry of Friedel pairs. Our observation highlights the role of spin-lattice coupling in routes towards ultrafast control of spin order.

Automated summary

The study investigates ultrafast lattice dynamics in NiO using femtosecond electron diffraction, identifying a nonthermal lattice state with preferential displacement of O compared to Ni ions. This nonthermal state occurs within approximately 0.3 ps and lasts for 25 ps, highlighting the role of spin-lattice coupling in achieving ultrafast control of spin order.