Spin Noise Spectroscopy of two-dimentional van der Waals antiferromagnets

• Applicant: Dr. Vladimir Kats
• Subject Area: Experimental Condensed Matter Physics
• Term: since 2024
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 540404622

Currently, two-dimensional (2D) van der Waals (vdW) nanomaterials are widely used in many different applications, such as the creation of electronic optoelectronic devices, batteries, supercapacitors, and solar cells. Among vdW materials, vdW magnets are unique in their great potential in the field of development of miniaturized electronic and magnonic applications. The main aim of this project is to study the spin dynamics in archetypical 2D vdW magnets, namely, antiferromagnets CrSBr and CrTe3. We will focus on spin dynamics in those crystals in temperature region up to phase transitions. Our main idea for temperature region below Neel temperatures is to investigate intrinsic magnon properties. The region of critical temperatures is the region of the most significant changes in the magneto-optical properties of materials. This is not only interesting from the fundamental point of view but also provides additional information on the formation of the correlated states in the intrinsic magnetization of the structures. Traditional optical methods for studying spin dynamics are perturbative and do not reveal the intrinsic properties of magnons. To solve those tasks we will use spin noise spectroscopy (SNS) method. SNS is a powerful nonperturbative method to obtain information about dynamics of various systems based on their spin fluctuations. Since studied materials are antiferromagnets, we expect magnetization precession in them at a frequency of the order of dozen of gigahertz and higher. Traditionally, SNS has been employed for measuring relatively slow spin fluctuation dynamics in paramagnets in the range of MHz to GHz frequencies. We are going to overcome this limitation by employing two synchronized picosecond laser oscillators as a stroboscopic optical sampling tool. This modification of the method allows one to study spin dynamics, initially having only an approximate idea about its frequency. The obtained results will significantly contribute to the development of magnonics in 2D vdW antiferromagnets and promote creation of novel photonic and optoelectronic devices.

• DFG Programme: WBP Position