Anomalous Transverse Thomson Effect

arXiv:2605.06299 · cond-mat.mes-hall · Submitted 2026-05-07 · Read on arXiv

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Introduction to the show: ident: Quantum Radio. Generated commentary on the latest quantum physics and condensed matter papers.

Kai: I'm Kai, and with me are Mira and Lev, guest researcher.

Mira: Today's paper: "Anomalous Transverse Thomson Effect".

Kai: The anomalous Thomson effect (ATE) is formulated as a Thomson counterpart to the anomalous Hall and Nernst effects, providing a mechanism for solid-state thermoelectric refrigeration in specific materials.

Mira: First, who's behind it and why it matters.

Title and authors: Kai: So we're looking at this paper, "Anomalous Transverse Thomson Effect," and it introduces something called the anomalous Thomson effect, which they frame as a counterpart to the anomalous Hall effect and anomalous Nernst effect.

Mira: It sounds like they're trying to create a mechanism for solid-state refrigeration using these effects in specific materials.

Kai: Right, so it suggests that if you apply a current and a temperature gradient perpendicularly, you can get this transverse thermal response.

Lev: From where I stand, this means we need to look at the underlying physics of how those currents and gradients interact with the material's magnetic properties.

The paper's summary: Mira: So, they summarize it by saying the anomalous Thomson coefficient, ATC, is determined by combining the anomalous Nernst coefficient, ANC, with how both of those things and electrical conductivity change with temperature.

Kai: That’s a bit more detail than just saying it's a counterpart to other effects. It seems like they're making a specific formula for this new effect based on what we already know about the ANC.

Mira: Exactly, and they state that this relationship is model independent within local linear response, meaning it should hold true regardless of whether the anomalous Nernst effect comes from intrinsic things or something extrinsic.

Lev: That's a big deal for experimentalists because it suggests we might be able to use existing measurements of conductivity and transport coefficients to predict this effect without having to develop a whole new microscopic model from scratch.

The paper's improvements: Kai: They also point out how the anomalous Thomson coefficient, ATC, gets its value from three different contributions when you look at the formula they have.

Mira: It breaks down into one term describing the temperature evolution of the ANC, and another term that comes from a local energy balance at that specific spot.

Kai: So it’s not just one simple relationship; it’s a combination of thermal changes and local energy considerations driving the effect.

Lev: That points to where we need to focus our attention for practical implementation, because understanding those separate contributions helps us figure out what's controlling the magnitude of the cooling or heating.

Conclusion: Mira: So, wrapping up, the paper suggests that this anomalous Thomson effect could be useful for solid-state thermoelectric refrigeration in materials where certain conditions are met.

Kai: And they show some specific examples, like CeCrGe3, where they found the ATC can be ten times larger than the ANC at liquid nitrogen temperatures.

Lev: For hardware design, that magnitude is what matters; having a factor of ten difference between these two coefficients opens up possibilities for much stronger cooling capabilities than we might expect from just looking at one effect alone.

Mira: Indeed, and they also mention how the dimensionless ratio of ATC to ANC converges to three in the low-temperature limit.

Kai: So, just to recap, this paper lays out a way to calculate this effect using known data and shows that for some materials like CeCrGe3, it could offer a substantial enhancement over other known anomalous effects.

Lev: It’s interesting because it connects the theory directly to the potential for real-world cooling performance.

School of Physical Sciences, University of Chinese Academy of Sciences, Beijing 100049, China. · Interdisciplinary Center for Theoretical Physics and Information Sciences (ICTPIS), Fudan University, Shanghai 200433, China. · School of Electronic, Electrical and Communication Engineering, University of Chinese Academy of Sciences, Beijing 100049, China. · Institute of Theoretical Physics, Chinese Academy of Sciences, Beijing 100190, China. · Kavli Institute for Theoretical Sciences, University of Chinese Academy of Sciences, Beijing 100190, China.

cond-mat.mes-hall

Submitted: 2026-05-07

Updated: 2026-10-09

Comments: 7 pages, 3 figures

License: http://arxiv.org/licenses/nonexclusive-distrib/1.0/

Importance score: 79/100

The gist: The anomalous Thomson effect (ATE) is formulated as a Thomson counterpart to the anomalous Hall and Nernst effects, providing a mechanism for solid-state thermoelectric refrigeration in specific

Key concepts

Anomalous Transverse Thomson Effect (ATTE)
The ATTE is a theoretical effect that acts as a Thomson counterpart to anomalous Hall and Nernst effects. It describes how an imposed current density interacts with temperature gradients in magnetic materials, providing a pathway for solid-state thermoelectric refrigeration.
Anomalous Nernst Coefficient (ANC)
The ANC quantifies the response of a material to a temperature gradient when subjected to a magnetic field. This coefficient is crucial because it is related to the ATTE; both are determined by the total ANC and its temperature dependence, regardless of whether its origin is intrinsic or extrinsic.
Berry Curvature
In topological materials like Fe3Sn2, Berry curvature arises from the band structure near gapped Dirac cones. The paper shows that this Berry curvature significantly enhances the contributions to the ANC-related terms of the ATTE, leading to stronger effects in these specific materials.
Longitudinal Resistivity
The temperature dependence of longitudinal resistivity plays an additional role in determining the ATTE coefficient, especially when considering equipotential electrodes. This dependence is necessary for fully determining $ au_{ m ATTE}^{(E)}$ and is model-independent within local linear response.

Terminology

Summary

The anomalous Thomson effect (ATE) is formulated as a Thomson counterpart to the anomalous Hall and Nernst effects, providing a mechanism for solid-state thermoelectric refrigeration in specific materials. The key finding is that the ratio ATC/ANC approaches three in the low-temperature limit, and for CeCrGe3, the ATC can be ten times larger than the ANC at liquid nitrogen temperatures.

How it works

The anomalous Thomson coefficient (ATC) is determined by the anomalous Nernst coefficient (ANC) together with the temperature dependence of both the ANC and the longitudinal electrical conductivity. This relation is model independent within local linear response and holds for the total anomalous Nernst coefficient, irrespective of whether its microscopic origin is intrinsic or extrinsic. The ATE arises when jc and ∇T are applied mutually perpendicularly in certain magnetic materials with spontaneous magnetization M and a finite omegak. Specifically, the ATE originates from the temperature evolution of the anomalous Ettingshausen heat current, where jc drives a transverse thermal current response jq along the direction of accumulated temperature gradient.

Formalism of the Anomalous Thomson Effect (ATE)

The volumetric heat generation rate is given by ˙qtot = Exjc,x − ∇yjq,y, and the ATE term is defined as q˙ATE = −τATE (M/M × jc) · ∇T. The anomalous Thomson coefficient (ATC) is obtained as τATE = TdS Axy/dT + 2S Axy + S AxyTd ln σxx/dT. This formula shows three contributions to the ATC. The first term describes the temperature evolution of the ANC, and the second term originates from local energy balance.

ATE in Dirac semimetal

Model calculations for topological layered kagome ferromagnet Fe3Sn2 show pronounced responses in both the Berry curvature-induced ANE and AHE. The analysis involves computing quantities like σxx, αxx, σAxy, and αAxy using the Boltzmann transport equation. For Fe3Sn2 with the specified Fermi energy pairs (εF 1,εF 2) =(73, 182) meV, the ATE coefficient τATE reaches a peak value of −18.2 µV/K around 389 K. The result reveals that the ATE-induced local cooling contribution is enhanced as the Fermi energy decreases, i.e., the closer εF to the Dirac point, the more pronounced the ATE occurs.

ATE coefficients for several realistic materials

Experimental data for CoS2, Co3Sn2S2, and CeCrGe3 are used to evaluate the ATC in several representative materials. CeCrGe3 exhibits an ATC reaching up to-20 µV /K, suggesting its potential as an excellent low-temperature refrigeration material. The dimensionless ratio η = τATE/SAxy converges to 3 in the low-temperature limit. Notably, CeCrGe3 exhibits both the largest S Axy and τATE among these three materials. In the liquid nitrogen temperature range, η for CeCrGe3 can exceed 10, indicating that the ATC is approximately 10 times larger than the ANC.

The Maximization of the Heat current jmax q

To connect the ATE term with an experimentally relevant quantity, a quantitative thermoelectric cooling capacity is considered using the maximum achievable cold-side heat current j max q x. This metric is governed by the dimensionless quantities zC TC = (S A C,yx)2TC / (ρ0κ′0) and ηC = τATE/SA C,yx. Equation (9) makes explicit that the ATE modifies the maximum cold-side heat current through ηC and β. This implies that the capacity of thermoelectric coolers can be enhanced through adjusting the material’s figure of merit, and by strategically harnessing the anomalous Thomson effect.

The gist

The anomalous Thomson effect (ATE) is formulated as a Thomson counterpart to the anomalous Hall and Nernst effects, providing a mechanism for solid-state thermoelectric refrigeration in specific materials. The key finding is that the ratio ATC/ANC approaches three in the low-temperature limit, and for CeCrGe3, the ATC can be ten times larger than the ANC at liquid nitrogen temperatures.

ATE in Dirac semimetal

Model calculations for topological layered kagome ferromagnet Fe3Sn2 show pronounced responses in both the Berry curvature-induced ANE and AHE.

Improvements for AI systems

  1. This improved system can predict optimal material choices for solid-state thermoelectric refrigeration by calculating the maximum cold-side heat current j max q,x using Equation (9), which makes explicit that the ATE modifies the maximum cold-side heat current through ηC and β.

  2. The AI can optimize Fermi level tuning for enhanced transverse heat absorption capacity by leveraging the findings in Figure 2(c), noting that the local heat absorption capacity, which is directly related to τATE, is optimized near the band edge, as demonstrated by the trend where τATE is monotonically increased as εF shifts closer to the conduction band edge.

  3. The system can quantify material performance comparisons by calculating a dimensionless ratio η = τATE/SA xy versus temperature T, allowing for direct comparison of refrigeration capabilities, such as observing that CeCrGe3 exhibits both the largest S Axy and τATE among these three materials in the liquid nitrogen range where η for CeCrGe3 can exceed 10.

  4. The AI can perform model-independent verification of anomalous effects by utilizing existing data, as the paper states that the formulated ATE can be directly verified using existing ANE and longitudinal conductivity data, without the need for additional equipment or measurements.

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