Enhanced thermoelectric performance of heavy-fermion compounds YbTM2Zn20 (TM = Co, Rh, Ir) at low temperatures

Kaya Wei; Jennifer N. Neu; You Lai; Kuan Wen Chen; Dean Hobbis; George S. Nolas; David E. Graf; Theo Siegrist; Ryan E. Baumbach

doi:10.1126/sciadv.aaw6183

Enhanced thermoelectric performance of heavy-fermion compounds YbTM₂Zn₂₀ (TM = Co, Rh, Ir) at low temperatures

Kaya Wei, Jennifer N. Neu, You Lai, Kuan Wen Chen, Dean Hobbis, George S. Nolas, David E. Graf, Theo Siegrist, Ryan E. Baumbach

Research output: Contribution to journal › Article › peer-review

13 Scopus citations

Abstract

Thermoelectricity allows direct conversion between heat and electricity, providing alternatives for green energy technologies. Despite these advantages, for most materials the energy conversion efficiency is limited by the tendency for the electrical and thermal conductivity to be proportional to each other and the Seebeck coefficient to be small. Here we report counter examples, where the heavy fermion compounds YbTM₂Zn₂₀ (TM = Co, Rh, Ir) exhibit enhanced thermoelectric performance including a large power factor (PF = 74 mW/cm-K²; TM = Ir) and a high figure of merit (ZT = 0.07; TM = Ir) at 35 K. The combination of the strongly hybridized electronic state originating from the Yb f-electrons and the novel structural features (large unit cell and possible soft phonon modes) leads to high power factors and small thermal conductivity values. This demonstrates that with further optimization these systems could provide a platform for the next generation of low temperature thermoelectric materials.

Original language	English
Article number	eaaw6183
Journal	Science Advances
Volume	5
Issue number	5
DOIs	https://doi.org/10.1126/sciadv.aaw6183
State	Published - May 31 2019
Externally published	Yes

Funding

This work was performed at the National High Magnetic Field Laboratory, which is supported by NSF Cooperative Agreement No. DMR-1644779 and the State of Florida. The synthesis of single crystals was supported by the Center for Actinide Science and Technology (CAST), an Energy Frontier Research Center funded by the U.S. Department of Energy, Office of Science, Basic Energy Sciences under award no. DESC0016568. K.W. acknowledges the support of the Jack E. Crow Postdoctoral Fellowship. J.N.N. and T.S. acknowledge support from the NSF under award NSF DMR-1606952. G.S.N. acknowledges support from the NSF (grant no. DMR-1748188). G.S.N. and D.H. also acknowledge support from the II-VI Foundation Block-Gift Program.

Funders	Funder number
National Science Foundation	DMR-1644779, DMR-1748188, DMR-1606952
Directorate for Mathematical and Physical Sciences	1748188
Basic Energy Sciences	DESC0016568
Center for Nanoscale Science and Technology

UN SDGs

This output contributes to the following UN Sustainable Development Goals (SDGs)

Access to Document

10.1126/sciadv.aaw6183

Cite this

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title = "Enhanced thermoelectric performance of heavy-fermion compounds YbTM2Zn20 (TM = Co, Rh, Ir) at low temperatures",

abstract = "Thermoelectricity allows direct conversion between heat and electricity, providing alternatives for green energy technologies. Despite these advantages, for most materials the energy conversion efficiency is limited by the tendency for the electrical and thermal conductivity to be proportional to each other and the Seebeck coefficient to be small. Here we report counter examples, where the heavy fermion compounds YbTM2Zn20 (TM = Co, Rh, Ir) exhibit enhanced thermoelectric performance including a large power factor (PF = 74 mW/cm-K2; TM = Ir) and a high figure of merit (ZT = 0.07; TM = Ir) at 35 K. The combination of the strongly hybridized electronic state originating from the Yb f-electrons and the novel structural features (large unit cell and possible soft phonon modes) leads to high power factors and small thermal conductivity values. This demonstrates that with further optimization these systems could provide a platform for the next generation of low temperature thermoelectric materials.",

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AU - Wei, Kaya

AU - Neu, Jennifer N.

AU - Lai, You

AU - Chen, Kuan Wen

AU - Hobbis, Dean

AU - Nolas, George S.

AU - Graf, David E.

AU - Siegrist, Theo

AU - Baumbach, Ryan E.

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AB - Thermoelectricity allows direct conversion between heat and electricity, providing alternatives for green energy technologies. Despite these advantages, for most materials the energy conversion efficiency is limited by the tendency for the electrical and thermal conductivity to be proportional to each other and the Seebeck coefficient to be small. Here we report counter examples, where the heavy fermion compounds YbTM2Zn20 (TM = Co, Rh, Ir) exhibit enhanced thermoelectric performance including a large power factor (PF = 74 mW/cm-K2; TM = Ir) and a high figure of merit (ZT = 0.07; TM = Ir) at 35 K. The combination of the strongly hybridized electronic state originating from the Yb f-electrons and the novel structural features (large unit cell and possible soft phonon modes) leads to high power factors and small thermal conductivity values. This demonstrates that with further optimization these systems could provide a platform for the next generation of low temperature thermoelectric materials.

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