Abstract
Magnetoresistive effects are pivotal for data storage technologies in modern electronics. Understanding those phenomena at THz frequencies is a crucial prerequisite for the transition of operational speeds from nanosecond to picosecond timescales. Current THz magnetoresistive research has been restricted almost exclusively to ferromagnets. We will reach beyond those conventional materials, where the magnetization dynamics is limited to GHz frequencies, by exploring antiferromagnetic materials which exhibit THz magnetization dynamics. Finally, we will focus on newly discovered altermagnetic materials, which combine the advantageous properties of both, spin-polarized band structure of ferromagnets and THz dynamics of antiferromagnets.
We will investigate three key magnetoresistive effects: Anisotropic Magnetoresistance (AMR), Giant Magnetoresistance (GMR), and Spin-Hall Magnetoresistance (SMR) using ultra-broadband THz time-domain spectroscopy. Initially, we will conduct experiments on ferromagnetic structures, which are easy to manipulate with external magnetic fields. Our preliminary results have revealed a never- before-observed time delay of 10 fs in the onset of GMR, corroborating the importance of phase-sensitive measurements. Subsequently, we will focus on antiferromagnetic materials to capture both electron and magnetization dynamics, and ultimately, we will apply the insights to altermagnetic materials. A deeper and more detailed understanding of magnetoresistive mechanisms in THz range will enable the construction of significantly faster and more efficient spintronic devices.
