We present a novel setup to measure the transverse magneto-optical Kerr effect in the extreme ultraviolet spectral range based on a fiber laser amplifier system with a repetition rate between 100 and 300 kHz, which we use to measure element-resolved demagnetization dynamics. The setup is equipped with a strong electromagnet and a cryostat, allowing measurements between 10 and 420 K using magnetic fields up to 0.86 T. The performance of our setup is demonstrated by a set of temperature- and time-dependent magnetization measurements with elemental resolution.

The colossal magnetoresistive manganite ${\left({\mathrm{La}}_{0.6}{\mathrm{Pr}}_{0.4}\right)}_{0.7}{\mathrm{Ca}}_{0.3}{\mathrm{MnO}}_3$ (LPCMO) undergoes a ferromagnetic (FM) metal to paramagnetic insulator phase transition at around 195 K, which develops via an intermediate polaronic state strongly susceptible to external magnetic fields. Transient reflectivity studies of LPCMO on timescales from sub-picoseconds to nanoseconds reveal that the overall system dynamics are strongly influenced by the phase transition with a sharp and strong decrease in the relaxation time while crossing from the ferromagnetic metallic phase into the paramagnetic insulating phase. We show that the long relaxation times of the reflectivity after nonequilibrium excitation within the FM phase are caused by the slow recovery of the ordered FM state after laser-induced demagnetization. Control of the nonequilibrium dynamics close to the phase transition is demonstrated by applying moderate magnetic fields below 1 T.

Superlattices (SLs) comprising layers of a soft ferromagnetic metal La_2/3Sr_1/3MnO₃ (LSMO) with in-plane (IP) magnetic easy axis and a hard ferromagnetic insulator La₂MnCoO₆ (LMCO, out-of-plane anisotropy) were grown on SrTiO₃ (100)(STO) substrates by a metalorganic aerosol deposition technique. Exchange spring magnetic (ESM) behavior between LSMO and LMCO, manifested by a spin reorientation transition of the LSMO layers towards perpendicular magnetic anisotropy below T_SR = 260 K, was observed. Further, 3ω measurements of the [(LMCO)₉/(LSMO)₉]₁₁/STO(100) superlattices revealed extremely low values of the cross-plane thermal conductivity κ(300 K) = 0.32 Wm⁻¹K⁻¹. Additionally, the thermal conductivity shows a peculiar dependence on the applied IP magnetic field, either decreasing or increasing in accordance with the magnetic disorder induced by ESM. Furthermore, both positive and negative magnetoresistance were observed in the SL in the respective temperature regions due to the formation of 90°-Néel domain walls within the ESM, when applying IP magnetic fields. The results are discussed in the framework of electronic contribution to thermal conductivity originating from the LSMO layers.

CZTS nanoparticle inks are synthesised and deposited as thin films by spin coating. We report variations in the chemical composition of films synthesised under nominally identical conditions, and the impact of annealing in a sulphur environment.

Spinodal decomposition in polycrystalline V_0.65Ti_0.35O₂ films yields a nanocomposite with V- and Ti-rich layers. Strain-enhanced thermochromism due to compression of V-rich phase decreases both the temperature and width of metal–insulator transition.

Ultrafast optical excitations allow creating new metastable and hidden states in quantum materials. However, the fundamental material properties required to support new emergent order are largely unknown. Here, we show for two colossal magnetoresistive (CMR) manganites that electronic phase separation (EPS) strongly favors nonthermal behavior and exploit this to stabilize an optically induced conducting state. Our results shed light on the role of EPS in the optical control of CMR manganites and provide guidance for the design of materials that can exhibit nonequilibrium states of matter. Published by the American Physical Society 2024