scholarly journals Anomalous Hall Heat Current and Nernst Effect in theCuCr2Se4−xBrxFerromagnet

2004 ◽  
Vol 93 (22) ◽  
Author(s):  
Wei-Li Lee ◽  
S. Watauchi ◽  
V. L. Miller ◽  
R. J. Cava ◽  
N. P. Ong
Keyword(s):  
Energy ◽  
2021 ◽  
Vol 217 ◽  
pp. 119403
Author(s):  
Tian Zhao ◽  
Xi Chen ◽  
Ke-Lun He ◽  
Qun Chen

Applied Nano ◽  
2021 ◽  
Vol 2 (3) ◽  
pp. 162-183
Author(s):  
Peter Markoš ◽  
Khandker Muttalib

We reviewed some recent ideas to improve the efficiency and power output of thermoelectric nano-devices. We focused on two essentially independent aspects: (i) increasing the charge current by taking advantage of an interplay between the material and the thermodynamic parameters, which is only available in the non-linear regime; and (ii) decreasing the heat current by using nanowires with surface disorder, which helps excite localized phonons at random positions that can strongly scatter the propagating phonons carrying the thermal current.


2021 ◽  
Vol 7 (13) ◽  
pp. eabf1467
Author(s):  
T. Asaba ◽  
V. Ivanov ◽  
S. M. Thomas ◽  
S. Y. Savrasov ◽  
J. D. Thompson ◽  
...  

The transverse voltage generated by a temperature gradient in a perpendicularly applied magnetic field, termed the Nernst effect, has promise for thermoelectric applications and for probing electronic structure. In magnetic materials, an anomalous Nernst effect (ANE) is possible in a zero magnetic field. We report a colossal ANE in the ferromagnetic metal UCo0.8Ru0.2Al, reaching 23 microvolts per kelvin. Uranium’s 5f electrons provide strong electronic correlations that lead to narrow bands, a known route to producing a large thermoelectric response. In addition, uranium’s strong spin-orbit coupling produces an intrinsic transverse response in this material due to the Berry curvature associated with the relativistic electronic structure. Theoretical calculations show that in UCo0.8Ru0.2Al at least 148 Weyl nodes, and two nodal lines, exist within 60 millielectron volt of the Fermi level. This work demonstrates that magnetic actinide materials can host strong Nernst and Hall responses due to their combined correlated and topological nature.


2020 ◽  
Vol 4 (2) ◽  
Author(s):  
Xiaodong Zhou ◽  
Jan-Philipp Hanke ◽  
Wanxiang Feng ◽  
Stefan Blügel ◽  
Yuriy Mokrousov ◽  
...  

2021 ◽  
Vol 11 (13) ◽  
pp. 5933
Author(s):  
Wei-Jen Chen ◽  
I-Ling Chang

This study investigated the thermal transport behaviors of branched carbon nanotubes (CNTs) with cross and T-junctions through non-equilibrium molecular dynamics (NEMD) simulations. A hot region was created at the end of one branch, whereas cold regions were created at the ends of all other branches. The effects on thermal flow due to branch length, topological defects at junctions, and temperature were studied. The NEMD simulations at room temperature indicated that heat transfer tended to move sideways rather than straight in branched CNTs with cross-junctions, despite all branches being identical in chirality and length. However, straight heat transfer was preferred in branched CNTs with T-junctions, irrespective of the atomic configuration of the junction. As branches became longer, the heat current inside approached the values obtained through conventional prediction based on diffusive thermal transport. Moreover, directional thermal transport behaviors became prominent at a low temperature (50 K), which implied that ballistic phonon transport contributed greatly to directional thermal transport. Finally, the collective atomic velocity cross-correlation spectra between branches were used to analyze phonon transport mechanisms for different junctions. Our findings deeply elucidate the thermal transport mechanisms of branched CNTs, which aid in thermal management applications.


2019 ◽  
Vol 2 (1) ◽  
Author(s):  
Conor N. Murphy ◽  
Paul R. Eastham

Abstract Lasers, photovoltaics, and thermoelectrically-pumped light emitting diodes are thermodynamic machines which use excitons (electron-hole pairs) as the working medium. The heat transfers in such devices are highly irreversible, leading to low efficiencies. Here we predict that reversible heat transfers between a quantum-dot exciton and its phonon environment can be induced by laser pulses. We calculate the heat transfer when a quantum-dot exciton is driven by a chirped laser pulse. The reversibility of this heat transfer is quantified by the efficiency of a heat engine in which it forms the hot stroke, which we predict to reach 95% of the Carnot limit. This performance is achieved by using the time-dependent laser-dressing of the exciton to control the heat current and exciton temperature. We conclude that reversible heat transfers can be achieved in excitonic thermal machines, allowing substantial improvements in their efficiency.


2007 ◽  
Vol 98 (7) ◽  
Author(s):  
Kamran Behnia ◽  
Marie-Aude Méasson ◽  
Yakov Kopelevich

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