TY - JOUR
T1 - Probing length-scale separation of thermal and spin currents by nanostructuring YIG
AU - Miura, Asuka
AU - Kikkawa, Takashi
AU - Iguchi, Ryo
AU - Uchida, Ken Ichi
AU - Saitoh, Eiji
AU - Shiomi, Junichiro
N1 - Funding Information:
The thermal conductivity measurement was performed using the facilities of the Cryogenic Research Center, the University of Tokyo. Structural characterization using EBSD was conducted at Advanced Characterization Nanotechnology Platform of the University of Tokyo supported by “Nanotechnology Platform” of the Ministry of Education, Culture, Sports, Science and Technology (MEXT), Japan. We thank S. Ito from Analytical Research Core for Advanced Materials, Institute for Materials Research, Tohoku University, for performing transmission electron microscopy on our samples. This work is partially supported by CREST “Scientific Innovation for Energy Harvesting Technology” (Grant No. JPMJCR16Q5); PRESTO “Phase Interfaces for Highly Efficient Energy Utilization” (Grant No. JPMJPR12C1) and ERATO “Spin Quantum Rectification Project” (Grant No. JPMJER1402) from JST, Japan; Grant-in-Aid for Scientific Research (B) (Grant No. JP16H04274) and (A) (Grant No. JP15H02012), Grant-in-Aid for Scientific Research on Innovative Area “Nano Spin Conversion Science” (Grant No. JP26103005) from JSPS KAKENHI, Japan; NEC Corporation; the Noguchi Institute; and E-IMR, Tohoku University. A.M. and T.K. are supported by JSPS through a research fellowship for young scientists (Grant No. JP16J09152 for A.M. and Grant No. JP15J08026 for T.K.).
PY - 2017/6/19
Y1 - 2017/6/19
N2 - We have fabricated bulk nanostructured ferrimagnetic materials with different grain sizes by sintering ball-milled Y3Fe5O12 (YIG) nanoparticles and measured the grain-size dependence of the thermal conductivity and spin Seebeck thermopower. The nanostructuring reduces both thermal conductivity and thermopower, but the reduction of the latter was found to be considerably stronger despite the moderate difference in magnetization, which suggests that the length scales of transport of magnons and phonons contributing to the spin Seebeck effect are significantly larger than that of phonons carrying thermal current. This is consistent with the measurements of high-magnetic-field response of the spin Seebeck thermopower and low-temperature thermal conductivity, where the quenching of magnons seen in single-crystalline YIG was not observed in nanostructured YIG due to scattering of long-range low frequency magnons.
AB - We have fabricated bulk nanostructured ferrimagnetic materials with different grain sizes by sintering ball-milled Y3Fe5O12 (YIG) nanoparticles and measured the grain-size dependence of the thermal conductivity and spin Seebeck thermopower. The nanostructuring reduces both thermal conductivity and thermopower, but the reduction of the latter was found to be considerably stronger despite the moderate difference in magnetization, which suggests that the length scales of transport of magnons and phonons contributing to the spin Seebeck effect are significantly larger than that of phonons carrying thermal current. This is consistent with the measurements of high-magnetic-field response of the spin Seebeck thermopower and low-temperature thermal conductivity, where the quenching of magnons seen in single-crystalline YIG was not observed in nanostructured YIG due to scattering of long-range low frequency magnons.
UR - http://www.scopus.com/inward/record.url?scp=85026269946&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=85026269946&partnerID=8YFLogxK
U2 - 10.1103/PhysRevMaterials.1.014601
DO - 10.1103/PhysRevMaterials.1.014601
M3 - Article
AN - SCOPUS:85026269946
VL - 1
JO - Physical Review Materials
JF - Physical Review Materials
SN - 2475-9953
IS - 1
M1 - 014601
ER -