Energy waste is a severe bottleneck in the supply of sustainable energy to any
modern economy. Besides developing new energy sources, the global energy
crisis can be alleviated by re-utilizing the waste heat. In this talk, I will first
introduce some background of harnessing the thermal energy by the
thermoelectrics, spin caloritronics, and phononics. Then, in the second part, I
would like to share with you some of my recent discoveries about the
rectification and negative differential spin Seebeck effects, exemplified in
metal/magnetic insulator interfaces and magnon tunneling junctions. These
properties lead us to the novel devices, such as thermal-driven spin diode and
transistor in the absence of electric transports. I call them spin Seebeck diode
and transistor. These findings imply that a spin computer driven by waste heat
might not be a dream in the future, which offer us new opportunities to achieve
the smart control of energy and information at nanoscale.
Finally, if time allows, I will briefly discuss the future research plan, which I name
Xonics, a cross-disciplinary field to achieve the multimode integration of
phononics, photonics, electronics, and magnonics (and so on) in hybrid quantum
materials and artificial/biologically-inspired nano-devices for efficient energy
transport, harvesting and information processing.