NMR study of the Peculiar Superconducting Mixed State in the Np Superconductor

2011 Fiscal Year Final Research Report

• Project/Area Number: 21740273
• Research Category: Grant-in-Aid for Young Scientists (B)
• Allocation Type: Single-year Grants
• Research Field: Condensed matter physics II
• Research Institution: Japan Atomic Energy Agency
• Principal Investigator: CHUDO Hiroyuki 独立行政法人日本原子力研究開発機構, 先端基礎研究センター, 任期付研究員 (30455282)
• Project Period (FY): 2009 – 2011
• Keywords: 核磁気共鳴 / 交差緩和 / 重い電子超伝導体 / アクチノイド化合物

Research Abstract

A^^<27> l nuclearspin-lattice relaxation rate 1/T^^<27>_1 has been measured in heavy fermion superconductor NpPd_5Al_2 for a wide range of external fields between 0.7 and 11T. We found that 1/T^^<27>_1 exhibits a strong, fields-dependence behavior at low field s below H^～ 3T, which is attributed to unlike-spin cross relaxation between N^^<237> p-A^^<27> l. An analysis based on the cross relaxation process allows us to make the first quantitative estimation of the Np nuclear relaxation rate 1/^<237>τin an itinerant 5f electron system. The estimated values of 1/^<237>τ^～ 6×10^7 s^<-1>, with a weak temperature variation, are below the resolution of NMR relaxation time, indicating that a direct observation of the N^^<237> p NMR signal would be very difficult, at least in the paramagnetic state. It is proposed that a direct observation of N^^<237> p NMR might be possible in the superconducting state at T^～ 1K.

Research Products

• [Journal Article] Observation of P^^<239> u Nuclear Magnetic Resonance (2012)
  • Author(s): H. Yasuoka, G. Koutroulakis, H. Chudo, S. Richmond, D. K. Veirs, A. I. Smith, E. D. Bauer, J. D. Thompson, G. D. Jarvinen, D. L. Clark
  • Journal Title: Science Volume: Vol.336 Pages: 901-904
  • DOI: DOI:10.1126/science.1220801
  • Peer Reviewed
• [Journal Article] N^^<237> pNuclear Relaxation Rate in Heavy Fermion Superconductor NpPd_5Al_2 (2011)
  • Author(s): H. Chudo, Y. Tokunaga, S. Kambe, H. Sakai, Y. Haga, T. D. Matsuda, Y. nuki, H. Yasuoka, D. Aoki, Y. Homma, R. E. Walstedt
  • Journal Title: Physical Review B Volume: Vol.84 Pages: 094402-1-094402-5
  • DOI: DOI:10.1103/PhysRevB.84.094402
  • Peer Reviewed
• [Journal Article] Anisotropic Spin Fluctuations in Heavy-Fermion Superconductor NpPd_5Al_2 (2010)
  • Author(s): H. Chudo, H. Sakai, Y. Tokunaga, S. Kambe, D. Aoki, Y. Homma, Y. Haga, T. D. Matsuda, Y. nuki, H. Yasuoka
  • Journal Title: Journal of the Physical Society of Japan Volume: Vol.79 Pages: 053704-1-053704-4
  • DOI: DOI:10.1143/JPSJ.79053704
  • Peer Reviewed
• [Journal Article] P^<105> dNQR Study on NpPd_5Al_2 and CePd_5Al_2 (2010)
  • Author(s): H. Chudo, H. Sakai, Y. Tokunaga, S. Kambe, D. Aoki, Y. Haga, T. D. Matsuda, Y. Homma, Y. Nakano, F. Honda, R. Settai, Y. nuki, H. Yasuoka
  • Journal Title: Journal of Physics : Conference Series Volume: Vol.200 Pages: 012020-1-012020-4
  • DOI: DOI:10.1088/1742-6596/200/1/012020
  • Peer Reviewed
• [Presentation] Np^^<273> Nuclear Relaxation rate in Heavy Fermion Superconductor NpPd_5Al_2 (2011)
  • Author(s): 中堂博之
  • Organizer: 新学術領域研究「重い電子系の形成と秩序化」第三回研究会
  • Place of Presentation: 千葉県
  • Year and Date: 2011-06-24
• [Presentation] NpPd_5Al_2におけるスピン揺らぎの異方性と超伝導 (2010)
  • Author(s): 中堂博之
  • Organizer: 日本物理学会2010年秋季大会
  • Place of Presentation: 大阪府
  • Year and Date: 2010-09-25