Observation of nuclear-spin Seebeck effect

• Published in: Nature communications Vol. 12; no. 1; p. 4356
• Main Authors: Kikkawa, T., Reitz, D., Ito, H., Makiuchi, T., Sugimoto, T., Tsunekawa, K., Daimon, S., Oyanagi, K., Ramos, R., Takahashi, S., Shiomi, Y., Tserkovnyak, Y., Saitoh, E.
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 16.07.2021; Nature Publishing Group; Nature Portfolio
• Subjects: 140/131; 639/301/119/1001; 639/766/119/1001; 639/766/119/995; 639/766/119/997; CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; Electric contacts; Electrons; Energy; Entropy; Excitation; Heat; Humanities and Social Sciences; Low temperature; Materials research; multidisciplinary; NUCLEAR PHYSICS AND RADIATION PHYSICS; Nuclear spin; Quenching; Science; Science (multidisciplinary); Seebeck effect; Temperature sensors; Thermoelectric power generation; Thermoelectricity
• ISSN: 2041-1723; 2041-1723
• DOI: 10.1038/s41467-021-24623-6

Thermoelectric effects have been applied to power generators and temperature sensors that convert waste heat into electricity. The effects, however, have been limited to electrons to occur, and inevitably disappear at low temperatures due to electronic entropy quenching. Here, we report thermoelectric generation caused by nuclear spins in a solid: nuclear-spin Seebeck effect. The sample is a magnetically ordered material MnCO 3 having a large nuclear spin ( I  = 5/2) of 55 Mn nuclei and strong hyperfine coupling, with a Pt contact. In the system, we observe low-temperature thermoelectric signals down to 100 mK due to nuclear-spin excitation. Our theoretical calculation in which interfacial Korringa process is taken into consideration quantitatively reproduces the results. The nuclear thermoelectric effect demonstrated here offers a way for exploring thermoelectric science and technologies at ultralow temperatures. Thermoelectric effects are limited to electrons to occur, and disappear at low temperatures due to electronic entropy quenching. Here, the authors report thermoelectric generation caused by nuclear spins down to 100 mK due to nuclear-spin excitation in a magnetically ordered material MnCO 3 .