Magneto-optical properties of multifunctional BaTiO₃-BiFeO₃ films and nano-rod arrays

In this work, we focused on probing optical properties of BaTiO₃-BiFeO₃ films and nano-rod arrays, by employing transient reflectivity and time resolved magneto-optical Kerr effect. We perfomed these measurements via pump/probe optical techniques in high external magnetic fields (up to 10 T). The pump laser was fixed at 400 nm (1 KHz repetition rate), which allowed us to generate Coherent Longitudinal Acoustic Phonons (CLAPs) within the samples, and we used 800 nm pulses as the probe beam. We obserevd strong sensitivity of CLAPs to the external magnetic fields, and we also observed coherent oscillations with frequencies, close to the predicted magnon frequencies. The ability to generate strain via ultrafast optics offers the intriguing possibility of dynamically manipulating the strain in a given sample with ultrashort optical pulses, and opens the possibility of creating a new class of devices, on the basis our less explored multiferroics, where the strain can be manipulated in time to control the properties and operation of a device.