Unconventional heavy-fermion superconductivity of a new transuranium compound NpPd 5Al 2

Dai Aoki; Yoshinori Haga; Tatsuma D. Matsuda; Naoyuki Tateiwa; Shugo Ikeda; Yoshiya Homma; Hironori Sakai; Yoshinobu Shiokawa; Etsuji Yamamoto; Akio Nakamura; Rikio Settai; Yoshichika Onuki

doi:10.1143/JPSJ.76.063701

Unconventional heavy-fermion superconductivity of a new transuranium compound NpPd ₅Al ₂

Dai Aoki, Yoshinori Haga, Tatsuma D. Matsuda, Naoyuki Tateiwa, Shugo Ikeda, Yoshiya Homma, Hironori Sakai, Yoshinobu Shiokawa, Etsuji Yamamoto, Akio Nakamura, Rikio Settai, Yoshichika Onuki

Materials Processing and Characterization Division

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

110 Citations (Scopus)

Abstract

We succeeded in growing a new transuranium compound NpPd ₅Al ₂ with the tetragonal crystal structure by the Pb-flux method, and measured the electrical resistivity, specific heat, magnetic susceptibility and magnetization. NpPd ₅Al ₂ is found to be a paramagnetic heavy-fermion superconductor with strong coupling ΔC=γT _c = 2:33 [T _c = 4:9K and γ = 200 mJ/(K ²·mol)]. The upper critical field H _c2 at 0K is large and highly anisotropic: H _c2(0) = 37 kOe for H ∥ [100] and H _c2(0) = 143 kOe for H ∥ [001]. H _c2 is found to be strongly suppressed by the magnetic field, and the magnetization curve indicates a step-like increase at H _c2, which are due to the paramagnetic effect. The low-temperature electronic specific heat approximately follows the T ³-dependence, indicating the existence of point nodes in the energy gap. The d-wave superconductivity with point nodes is most likely realized in this compound.

Original language	English
Article number	063701
Journal	journal of the physical society of japan
Volume	76
Issue number	6
DOIs	https://doi.org/10.1143/JPSJ.76.063701
Publication status	Published - 2007 Jun

Keywords

Heavy-fermion superconductivity
Non-Fermi liquid
NpPd Al
Paramagnetic effect

ASJC Scopus subject areas

Physics and Astronomy(all)

Access to Document

10.1143/JPSJ.76.063701

Cite this

Unconventional heavy-fermion superconductivity of a new transuranium compound NpPd ₅Al ₂ . / Aoki, Dai; Haga, Yoshinori; Matsuda, Tatsuma D.; Tateiwa, Naoyuki; Ikeda, Shugo; Homma, Yoshiya; Sakai, Hironori; Shiokawa, Yoshinobu; Yamamoto, Etsuji; Nakamura, Akio; Settai, Rikio; Onuki, Yoshichika.

In: journal of the physical society of japan, Vol. 76, No. 6, 063701, 06.2007.

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

Aoki, Dai ; Haga, Yoshinori ; Matsuda, Tatsuma D. ; Tateiwa, Naoyuki ; Ikeda, Shugo ; Homma, Yoshiya ; Sakai, Hironori ; Shiokawa, Yoshinobu ; Yamamoto, Etsuji ; Nakamura, Akio ; Settai, Rikio ; Onuki, Yoshichika. / Unconventional heavy-fermion superconductivity of a new transuranium compound NpPd ₅Al ₂ In: journal of the physical society of japan. 2007 ; Vol. 76, No. 6.

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abstract = "We succeeded in growing a new transuranium compound NpPd 5Al 2 with the tetragonal crystal structure by the Pb-flux method, and measured the electrical resistivity, specific heat, magnetic susceptibility and magnetization. NpPd 5Al 2 is found to be a paramagnetic heavy-fermion superconductor with strong coupling ΔC=γT c = 2:33 [T c = 4:9K and γ = 200 mJ/(K 2·mol)]. The upper critical field H c2 at 0K is large and highly anisotropic: H c2(0) = 37 kOe for H ∥ [100] and H c2(0) = 143 kOe for H ∥ [001]. H c2 is found to be strongly suppressed by the magnetic field, and the magnetization curve indicates a step-like increase at H c2, which are due to the paramagnetic effect. The low-temperature electronic specific heat approximately follows the T 3-dependence, indicating the existence of point nodes in the energy gap. The d-wave superconductivity with point nodes is most likely realized in this compound.",

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author = "Dai Aoki and Yoshinori Haga and Matsuda, {Tatsuma D.} and Naoyuki Tateiwa and Shugo Ikeda and Yoshiya Homma and Hironori Sakai and Yoshinobu Shiokawa and Etsuji Yamamoto and Akio Nakamura and Rikio Settai and Yoshichika Onuki",

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AB - We succeeded in growing a new transuranium compound NpPd 5Al 2 with the tetragonal crystal structure by the Pb-flux method, and measured the electrical resistivity, specific heat, magnetic susceptibility and magnetization. NpPd 5Al 2 is found to be a paramagnetic heavy-fermion superconductor with strong coupling ΔC=γT c = 2:33 [T c = 4:9K and γ = 200 mJ/(K 2·mol)]. The upper critical field H c2 at 0K is large and highly anisotropic: H c2(0) = 37 kOe for H ∥ [100] and H c2(0) = 143 kOe for H ∥ [001]. H c2 is found to be strongly suppressed by the magnetic field, and the magnetization curve indicates a step-like increase at H c2, which are due to the paramagnetic effect. The low-temperature electronic specific heat approximately follows the T 3-dependence, indicating the existence of point nodes in the energy gap. The d-wave superconductivity with point nodes is most likely realized in this compound.

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