Spin Caloritronic Transport of Tree-Saw Graphene Nanoribbons

Using density functional theory combined with non-equilibrium Green's function method, we investigate the spin caloritronic transport properties of tree-saw graphene nanoribbons. These systems have stable ferromagnetic ground states with a high Curie temperature that is far above room temperature and exhibit obvious spin-Seebeck effect. Moreover, thermal colossal magnetoresistance up to 1020% can be achieved by the external magnetic field modulation. The underlying mechanism is analyzed by spin-resolved transmission spectra, current spectra and band structures.

Spin Caloritronic Transport of 1,3,5-Triphenylverdazyl Radical

We investigate theoretically the spin caloritronic transport properties of a stable 1,3,5-triphenylverdazyl （TPV） radical sandwiched between Au electrodes through different connection fashions. Obvious spin Seebeck effect can be observed in the para-eonnection fashion. Furthermore, a pure spin current and a completely spin-polarized current can be realized by tuning the gate voltage. Furthermore, a 100% spin polarization without the need of gate voltage can be obtained in the meta-conneetion fashion. These results demonstrate that TPV radical is a promising material for spin caloritronic and spintronic applications.

Spin Caloritronic Transport of (2×1) Reconstructed Zigzag MoS_2 Nanoribbons

Using first-principles density functional theory combined with nonequilibrium Green＇s function method, we inves-tigate the spin caloritronic transport properties of （2×1） reconstructed zigzag MoS2 nanoribbons. These systems can exhibit obvious spin Seebeck effect. Furthermore, by tuning the external magnetic field, a thermal giant magnetoresistance up to 10^4% can be achieved. These spin caloritronic transport properties are understood in terms of spin-resolved transmission spectra, band structures, and the symmetry analyses of energy bands around the Fermi level.

Progress of microscopic thermoelectric effects studied by micro- and nano-thermometric techniques

Heat dissipation is one of the most serious problems in modern integrated electronics with the continuously decreasing devices size. Large portion of the consumed power is inevitably dissipated inthe form of waste heat which not only restricts the device energy-efficiency performance itself, butalso leads to severe environment problems and energy crisis. Thermoelectric Seebeck effect is a greenenergy-recycling method, while thermoelectric Peltier effect can be employed for heat management byactively cooling overheated devices, where passive cooling by heat conduction is not sufficiently enough.However, the technological applications of thermoelectricity are limited so far by their very low conversion efficiencies and lack of deep understanding of thermoelectricity in microscopic levels. Probingand managing the thermoelectricity is therefore fundamentally important particularly in nanoscale. Inthis short review, we will first briefly introduce the microscopic techniques for studying nanoscale thermoelectricity, focusing mainly on scanning thermal microscopy (SThM). SThM is a powerful tool formapping the lattice heat with nanometer spatial resolution and hence detecting the nanoscale thermaltransport and dissipation processes. Then we will review recent experiments utilizing these techniques to investigate thermoelectricity in various nanomaterial systems including both (two-material)heterojunctions and (single-material) homojunctions with tailored Seebeck coefficients, and also spinSeebeck and Peltier effects in magnetic materials. Next, we will provide a perspective on the promisingapplications of our recently developed Scanning Noise Microscope (SNoiM) for directly probing thenon-equilibrium transporting hot charges (instead of lattice heat) in thermoelectric devices. SNoiMtogether with SThM are expected to be able to provide more complete and comprehensive understanding to the microscopic mechanisms in thermoelectrics. Finally, we make a conclusion and outlook onthe future development of microscopic studies in thermoelectrics.