[10p-S302-1~18] 10.2 Fundamental and exploratory device technologies for spin

▲ [10p-S302-3] Observation of nuclear-spin Seebeck effect

〇Takashi Kikkawa^1,2,3, Derek Reitz⁴, Hiroaki Ito¹, Takahiko Makiuchi¹, Takahiro Sugimoto¹, Kakeru Tsunekawa¹, Shunsuke Daimon¹, Koichi Oyanagi^3,5, Rafael Ramos², Saburo Takahashi², Yuki Shiomi⁶, Yaroslav Tserkovnyak⁴, Eiji Saitoh^1,2,3,7 (1.Dep. Appl. Phys. Univ. Tokyo, 2.AIMR Tohoku Univ., 3.IMR Tohoku Univ., 4.UCLA, 5.Fac. Sci. Eng. Iwate Univ., 6.Dep. Basic Sci. Univ. Tokyo, 7.ASRC JAEA)

Keywords:spin Seebeck effect

We report the observation of the thermoelectric effect powered by nuclear spins in a solid: nuclear spin-Seebeck effect (SSE). The sample system consists of an antiferromagnetic insulator MnCO₃, having a large nuclear spin I = 5/2 of ⁵⁵Mn and strong hyperfine interaction, with a Pt contact. In this Pt/MnCO₃ system, we found strong enhancement of SSE voltages down to 100 mK, which is not suppressed by the strong field of ~ 10 T, distinct from conventional electronic SSEs. The voltage feature is attributed to the highly-entropic nuclear spin excitation of MnCO₃ having the tiny energy scale of ~ 10 mK. The experimental result was quantitatively reproduced by a nuclear spin-current theory in which interfacial hyperfine interaction between Pt and MnCO₃ is taken into account.