A calorimetric investigation of RbFeb>2 b>Asb>2 b> single crystals
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- 作者：Seunghyun Khim ; Saicharan Aswartham ; Vadim Grinenko ; Dmitry Efremov ; Christian G. F. Blum ; Frank Steckel ; Daniel Gruner ; Anja U. B. Wolter ; Stefan-Ludwig Drechsler ; Christian Heß ; Sabine Wurmehl and Bernd Bü ; chner
- 刊名：physica status solidi (b)
- 出版年：2017
- 出版时间：January 2017
- 年：2017
- 卷：254
- 期：1
- 全文大小：625K
- ISSN：1521-3951
文摘
We present properties of single crystals of the iron pnictide superconductor RbFeb>2 b>Asb>2 b> grown using a self-flux method. A bulk superconducting transition at ruct="true" class="math-equation-construct">rue" class="math-equation-image">hml="true" class="math-equation-mathml" style="display:none">h xmlns:mml="http://www.w3.org/1998/Math/MathML">b xmlns:w="http://www.wiley.com/namespaces/wiley" xmlns:wiley="http://www.wiley.com/namespaces/wiley/wiley" xmlns:cr="urn://wiley-online-library/content/render" xmlns="http://www.w3.org/1998/Math/MathML">T c b> h> ruct="true" class="math-equation-construct">rue" class="math-equation-image">hml="true" class="math-equation-mathml" style="display:none">h xmlns:mml="http://www.w3.org/1998/Math/MathML">http://www.wiley.com/namespaces/wiley" xmlns:wiley="http://www.wiley.com/namespaces/wiley/wiley" xmlns:cr="urn://wiley-online-library/content/render" xmlns="http://www.w3.org/1998/Math/MathML">∼ h>2.6 K was consistently observed in resistivity, magnetic susceptibility, and specific heat measurements. While the resistivity behaves like a conventional metal at low T, the magnetic susceptibility shows an unusual broad maximum around 80 K in the normal state. A large Sommerfeld coefficient, ruct="true" class="math-equation-construct">rue" class="math-equation-image">hml="true" class="math-equation-mathml" style="display:none">h xmlns:mml="http://www.w3.org/1998/Math/MathML">b xmlns:w="http://www.wiley.com/namespaces/wiley" xmlns:wiley="http://www.wiley.com/namespaces/wiley/wiley" xmlns:cr="urn://wiley-online-library/content/render" xmlns="http://www.w3.org/1998/Math/MathML">γ 0 b>http://www.wiley.com/namespaces/wiley" xmlns:wiley="http://www.wiley.com/namespaces/wiley/wiley" xmlns:cr="urn://wiley-online-library/content/render" xmlns="http://www.w3.org/1998/Math/MathML">= http://www.wiley.com/namespaces/wiley" xmlns:wiley="http://www.wiley.com/namespaces/wiley/wiley" xmlns:cr="urn://wiley-online-library/content/render" xmlns="http://www.w3.org/1998/Math/MathML">127 http://www.wiley.com/namespaces/wiley" xmlns:wiley="http://www.wiley.com/namespaces/wiley/wiley" xmlns:cr="urn://wiley-online-library/content/render" xmlns="http://www.w3.org/1998/Math/MathML" width="thinmathspace"> http://www.wiley.com/namespaces/wiley" xmlns:wiley="http://www.wiley.com/namespaces/wiley/wiley" xmlns:cr="urn://wiley-online-library/content/render" xmlns="http://www.w3.org/1998/Math/MathML" mathvariant="normal">mJ http://www.wiley.com/namespaces/wiley" xmlns:wiley="http://www.wiley.com/namespaces/wiley/wiley" xmlns:cr="urn://wiley-online-library/content/render" xmlns="http://www.w3.org/1998/Math/MathML">/ http://www.wiley.com/namespaces/wiley" xmlns:wiley="http://www.wiley.com/namespaces/wiley/wiley" xmlns:cr="urn://wiley-online-library/content/render" xmlns="http://www.w3.org/1998/Math/MathML">row>hvariant="normal">mol K row>2 h>, was observed seemingly a common feature of heavily hole-doped “122” compounds. In the superconducting state, we analyzed our specific heat data based on the s- and d-wave two-gap models. The presence of the small gap with 2ruct="true" class="math-equation-construct">rue" class="math-equation-image">hml="true" class="math-equation-mathml" style="display:none">h xmlns:mml="http://www.w3.org/1998/Math/MathML">b xmlns:w="http://www.wiley.com/namespaces/wiley" xmlns:wiley="http://www.wiley.com/namespaces/wiley/wiley" xmlns:cr="urn://wiley-online-library/content/render" xmlns="http://www.w3.org/1998/Math/MathML">Δ 1 b>http://www.wiley.com/namespaces/wiley" xmlns:wiley="http://www.wiley.com/namespaces/wiley/wiley" xmlns:cr="urn://wiley-online-library/content/render" xmlns="http://www.w3.org/1998/Math/MathML" stretchy="false">( http://www.wiley.com/namespaces/wiley" xmlns:wiley="http://www.wiley.com/namespaces/wiley/wiley" xmlns:cr="urn://wiley-online-library/content/render" xmlns="http://www.w3.org/1998/Math/MathML">0 http://www.wiley.com/namespaces/wiley" xmlns:wiley="http://www.wiley.com/namespaces/wiley/wiley" xmlns:cr="urn://wiley-online-library/content/render" xmlns="http://www.w3.org/1998/Math/MathML" stretchy="false">) h>/ruct="true" class="math-equation-construct">rue" class="math-equation-image">hml="true" class="math-equation-mathml" style="display:none">h xmlns:mml="http://www.w3.org/1998/Math/MathML">b xmlns:w="http://www.wiley.com/namespaces/wiley" xmlns:wiley="http://www.wiley.com/namespaces/wiley/wiley" xmlns:cr="urn://wiley-online-library/content/render" xmlns="http://www.w3.org/1998/Math/MathML">k B b>b xmlns:w="http://www.wiley.com/namespaces/wiley" xmlns:wiley="http://www.wiley.com/namespaces/wiley/wiley" xmlns:cr="urn://wiley-online-library/content/render" xmlns="http://www.w3.org/1998/Math/MathML">T c b>http://www.wiley.com/namespaces/wiley" xmlns:wiley="http://www.wiley.com/namespaces/wiley/wiley" xmlns:cr="urn://wiley-online-library/content/render" xmlns="http://www.w3.org/1998/Math/MathML">< http://www.wiley.com/namespaces/wiley" xmlns:wiley="http://www.wiley.com/namespaces/wiley/wiley" xmlns:cr="urn://wiley-online-library/content/render" xmlns="http://www.w3.org/1998/Math/MathML">1 h> was discussed to account for the large specific heat contribution remaining to low T far below ruct="true" class="math-equation-construct">rue" class="math-equation-image">hml="true" class="math-equation-mathml" style="display:none">h xmlns:mml="http://www.w3.org/1998/Math/MathML">b xmlns:w="http://www.wiley.com/namespaces/wiley" xmlns:wiley="http://www.wiley.com/namespaces/wiley/wiley" xmlns:cr="urn://wiley-online-library/content/render" xmlns="http://www.w3.org/1998/Math/MathML">T c b> h>. The large ruct="true" class="math-equation-construct">rue" class="math-equation-image">hml="true" class="math-equation-mathml" style="display:none">h xmlns:mml="http://www.w3.org/1998/Math/MathML">b xmlns:w="http://www.wiley.com/namespaces/wiley" xmlns:wiley="http://www.wiley.com/namespaces/wiley/wiley" xmlns:cr="urn://wiley-online-library/content/render" xmlns="http://www.w3.org/1998/Math/MathML">H row>c 2 row> b> h> anisotropy ratio, ruct="true" class="math-equation-construct">rue" class="math-equation-image">hml="true" class="math-equation-mathml" style="display:none">h xmlns:mml="http://www.w3.org/1998/Math/MathML">b xmlns:w="http://www.wiley.com/namespaces/wiley" xmlns:wiley="http://www.wiley.com/namespaces/wiley/wiley" xmlns:cr="urn://wiley-online-library/content/render" xmlns="http://www.w3.org/1998/Math/MathML">Γ H b> h> = ruct="true" class="math-equation-construct">rue" class="math-equation-image">hml="true" class="math-equation-mathml" style="display:none">h xmlns:mml="http://www.w3.org/1998/Math/MathML">bsup xmlns:w="http://www.wiley.com/namespaces/wiley" xmlns:wiley="http://www.wiley.com/namespaces/wiley/wiley" xmlns:cr="urn://wiley-online-library/content/render" xmlns="http://www.w3.org/1998/Math/MathML">H row>c 2 row>hvariant="italic">ab bsup> h>/ruct="true" class="math-equation-construct">rue" class="math-equation-image">hml="true" class="math-equation-mathml" style="display:none">h xmlns:mml="http://www.w3.org/1998/Math/MathML">bsup xmlns:w="http://www.wiley.com/namespaces/wiley" xmlns:wiley="http://www.wiley.com/namespaces/wiley/wiley" xmlns:cr="urn://wiley-online-library/content/render" xmlns="http://www.w3.org/1998/Math/MathML">H row>c 2 row>c bsup> h> ruct="true" class="math-equation-construct">rue" class="math-equation-image">hml="true" class="math-equation-mathml" style="display:none">h xmlns:mml="http://www.w3.org/1998/Math/MathML">http://www.wiley.com/namespaces/wiley" xmlns:wiley="http://www.wiley.com/namespaces/wiley/wiley" xmlns:cr="urn://wiley-online-library/content/render" xmlns="http://www.w3.org/1998/Math/MathML">∼ h> 7 near ruct="true" class="math-equation-construct">rue" class="math-equation-image">hml="true" class="math-equation-mathml" style="display:none">h xmlns:mml="http://www.w3.org/1998/Math/MathML">b xmlns:w="http://www.wiley.com/namespaces/wiley" xmlns:wiley="http://www.wiley.com/namespaces/wiley/wiley" xmlns:cr="urn://wiley-online-library/content/render" xmlns="http://www.w3.org/1998/Math/MathML">T c b> h> indicates that the large gap would occupy a highly two-dimensional Fermi surface.