Spin transport and spin dynamics in two-dimensional magnetic insulators and transition metal dichalcogenides
In his thesis, Tian Liu investigates spin transport and spin dynamics in two-dimensional (2D) magnetic insulators and transition metal dichalcogenides (TMDs), focusing on their potential in next-generation spintronic devices. Liu explains the theoretical foundations of spin physics, introducing core concepts such as spin currents, spin accumulation, spin relaxation, and magnetoresistance. Key mechanisms—including the Spin Hall Effect, Rashba–Edelstein Effect, and Bilinear Magnetoresistance—are discussed as fundamental tools for the electrical generation and detection of spin signals.
Experimentally, Liu developed advanced device fabrication methods using hexagonal boron nitride (h-BN), chromium tribromide (CrBr₃), and tungsten ditelluride (WTe₂). Through spin pumping, angular-dependent magnetoresistance, and ferromagnetic resonance measurements, he explored how spins behave and interact in these materials.
Major findings include the first demonstration of spin caloritronic effects in CrBr₃/Pt heterostructures, revealing thermal magnon transport and magnetic proximity effects dominated by the spin Seebeck effect. Furthermore, Liu shows that crystallographic-dependent bilinear magnetoelectric resistance in WTe₂ enables tunable spin–charge conversion via crystal orientation. Finally, phase-sensitive voltage generation in WTe₂/YIG systems demonstrates coherent spin–charge interactions at GHz frequencies.
Together, these results deepen the understanding of spin behavior in 2D materials and provide possibilities for designing efficient, phase-sensitive spintronic technologies.