Observation of superconductivity in the noncentrosymmetric nodal chain semimetal Ba 5In4Bi5 Yuzhe Ma12 Yulong Wang12 Yuxin Wang12 Soham Manni34 Qisheng Lin35 Linlin

2025-05-02 0 0 1.42MB 30 页 10玖币

侵权投诉

Observation of superconductivity in the noncentrosymmetric

nodal chain semimetal Ba5In4Bi5

Yuzhe Ma1,2, Yulong Wang1,2, Yuxin Wang1,2, Soham Manni3,4, Qisheng Lin3,5, Linlin

Wang3,4, Kun Jiang1,2, Sergey L. Bud’ko3,4, Paul C. Canfield3,4, Gang Wang1,2,3,6

1 Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese

Academy of Sciences, Beijing 100190, China

2 University of Chinese Academy of Sciences, Beijing 100049, China

3 Ames National Laboratory, Iowa State University, Ames, Iowa 50011, USA

4 Department of Physics and Astronomy, Iowa State University, Ames, Iowa 50011, USA

5 Department of Chemistry, Iowa State University, Ames, Iowa 50011, USA

6 Songshan Lake Materials Laboratory, Dongguan, Guangdong 523808, China

The combination with superconductivity and topological nontrivial band structure

provides a promising route towards novel quantum states such as topological

superconductivity. Here, we report the first observation of superconductivity (4.1 K) in

Ba5In4Bi5 single crystal, a noncentrosymmetric topological semimetal featuring nodal

chain loops at the high-symmetry points R and X. The magnetization, resistivity, and

specific heat capacity measurements reveal that Ba5In4Bi5 is a moderately coupled type-

II Bardeen-Cooper-Schrieffer superconductor. Bulk superconductivity is suggested

from the magnetic susceptibility and specific heat measurements. The results show that

Ba5In4Bi5 provides a new platform for exploring the relationship of superconductivity

and topological nontrivial band topology.

gangwang@iphy.ac.cn

The fascinating development in topological quantum matter during the last two

decades has spurred a rush in exploring the emerging topological superconductivity

(TSC) in condensed matter physics, which provides a promising avenue for the

actualization of Majorana fermions. Two ways towards realizing TSC have been

adopted: finding superconductivity (SC) with intrinsic nontrivial topology or

combining the conventional SC with other nontrivial topological band structures. The

search for intrinsic TSC, such as the px+ipy spin-triplet SC (e.g., Sr2RuO4, UTe2) [1-4],

has been very challenging. Recently, the searching for intrinsic TSC has been extended

to superconducting topological materials via chemical doping or intercalation, e.g., the

doped topological insulators Cu/Sr-doped Bi2Se3 [5-10], In-doped SnTe [11], and doped

Weyl semimetals [12], which require fine tuning in composition and inevitably consist

of defects. Besides, the TSCs have been also explored on the interface of a

heterostructure between an s-wave superconductor and a strong topological insulator

(e.g., Bi2Se3/NbSe2, Bi2Te3/NbSe2) [13,14], or fully-gapped bulk SC connate with

topological surface states (e.g., FeTe1-xSex, 2M-WS2, and TaSe3) [15-19] based on the

superconducting proximity effect. Based on the discussion above, type-II

superconductors with nontrivial surface states are promising candidates for TSCs.

Therefore, it is highly desirable to explore new materials having both nontrivial band

topology and intrinsic SC.

As a special nodal line, nodal chain consisting of connected loops that touch each

other at isolated points on a high-symmetry axis, aroused the interest of Bzdušek et al.

in 2016, and they proposed that such nodal chains could emerge in materials with the

space groups of 102, 104, 109, 118, and 122 [20]. To this point, Ba5In4Bi5 has attracted

our attention: Ba5In4Bi5 has been reported to be a Pauli paramagnetic semimetal

crystalizing in a noncentrosymmetric tetragonal space group P4nc (No. 104) [21]. Very

recently, it has been predicted to possess Weyl nodal line close to the Fermi energy [22].

In this work, we have successfully grown the topological nodal chain semimetal

Ba5In4Bi5 single crystals by a flux method and observed the SC for the first time, which

is a type-II moderately coupled superconductor with a superconducting transition

temperature (Tc) about 4.1 K. The in-plane and out-plane upper critical field shows

weak anisotropy due to the three-dimensional nature of crystal structure. The observed

superconducting shielding fraction and the jump of specific heat capacity at 4.1 K

strongly suggest bulk superconductivity in Ba5In4Bi5. The presence of intrinsic SC in a

possible topologically nontrivial state makes Ba5In4Bi5 a new platform to study the

interplay of topological nodal chain and SC. In addition, the lack of the inversion

symmetry in the structure might result in the discovery of noncentrosymmetric

superconductor with mixed spin-singlet and spin-triplet SCs [23].

Ba5In4Bi5 crystallizes in a tetragonal structure with the noncentrosymmetric space

group P4nc (No. 104). The structure features isolated heteroatomic, square pyramidal

[In4Bi5]10- anionic clusters that are separated by Ba2+ cations. Each of the four In1 base

atoms in the square pyramidal [In4Bi5]10- clusters is exo-bound to Bi1 atom in a distance

of 2.9106(14) Å, in contrast, the base-to-apex In1-Bi2 distance of the pyramid is about

0.41 Å longer, 3.3212(19) Å (cf. Table S3). Moreover, adjacent square pyramids are

shifted by c/2 and rotated by 16.4 degrees with respect to each other along the c axis,

which reduces the overall symmetry of the crystal structure from body-centered to the

tetragonal primitive unit cell. In addition, Bi2 has a similar coordination environment

with that of Ba2, as can be seen from the right panel of Fig. 1(a). From Fig. S1(b), the

neighboring pyramids are stacked vertically along the c axis and linked via Bi1 atoms

and In1 atoms from different pyramids. The Bi1-In1 bonding distance is 3.3830(13) Å,

which is close to the bonding distance of 3.3212(19) Å between Bi2 atoms and In1

atoms within the pyramids, so the interaction between the nearest neighboring clusters

can’t be ignored. What’s more, Ba5In4Bi5 is an electron-deficient compound. In

electron-deficient compounds, Madelung energy and packing efficiency become more

dominant than covalent bonding [21]. In order to further study this one-electron-

deficient compound, we calculated the electronic band structure of Ba5In4Bi5 with spin-

orbit coupling (SOC) using the first-principles calculations, with details described in

Supplemental Material. Figure S2(b) presents an overview of the band structure and

density of states (DOS) of Ba5In4Bi5. Close to the Fermi level, the major contribution

to the DOS originates from Bi. A zoom-in view of the bands along the -X-R path with

SOC, shown in Fig. 1(b), reveals a band crossing along the -X direction and a twofold

degeneracy along the X-R direction, forming two Weyl nodal loops centered at R and

X points. The band crossing and the twofold degeneracy can be clearly seen on the right

of Fig. 1(b). The nodal loops touch each other, as displayed in Fig. 1(c) and discussed

in reference [22]. Notably the crossing along the -X direction of the Weyl nodal loop

is very close and only 5 meV below the Fermi energy.

FIG. 1. (a) The schematic crystal structure of Ba5In4Bi5 and the coordination

environment of Bi2 and Ba2 in the unit cell. (b) The electronic band structure of

Ba5In4Bi5 along the -X-R path with SOC. Right (Ⅰ) and (Ⅱ): Zoom-in band structures

of crossing and twofold degeneracy. (c) The illustration of the Weyl nodal chain along

the kz direction centered on the R and X points, respectively, which is formed by the

energy bands in (b). Yellow: the nodal loops protected by the mirror plane as defined

by kx = 0 or ky = 0. Green: the nodal loops protected by the mirror plane as defined by

kx = π or ky = π.

Inspired by the calculations, we grew Ba5In4Bi5 single crystals by the flux method

and studied their physical properties (See the supplementary material for details).

Before we perform measurements, the crystals were stored in an argon-filled glove box

to avoid sample degradation because, by visual inspection, they turn into black after

exposure in air for 1 h. The crystal structure data of Ba5In4Bi5 determined from single

crystal X-ray diffraction are given in Table S1-S4. The lattice parameters of Ba5In4Bi5

文档加载中……请稍候！
如果长时间未打开，您也可以点击刷新试试。

下载文档到电脑，查找使用更方便

10 玖币 0人已下载

立即下载

摘要：

ObservationofsuperconductivityinthenoncentrosymmetricnodalchainsemimetalBa5In4Bi5YuzheMa1,2,YulongWang1,2,YuxinWang1,2,SohamManni3,4,QishengLin3,5,LinlinWang3,4,KunJiang1,2,SergeyL.Bud’ko3,4,PaulC.Canfield3,4,GangWang1,2,3,6*1BeijingNationalLaboratoryforCondensedMatterPhysics,InstituteofPhysics,Chin...

展开>> 收起<<

Observation of superconductivity in the noncentrosymmetric nodal chain semimetal Ba 5In4Bi5 Yuzhe Ma12 Yulong Wang12 Yuxin Wang12 Soham Manni34 Qisheng Lin35 Linlin.pdf

共30页,预览5页

还剩页未读，继续阅读

声明：本站为文档C2C交易模式，即用户上传的文档直接被用户下载，本站只是中间服务平台，本站所有文档下载所得的收益归上传人(含作者)所有。玖贝云文库仅提供信息存储空间，仅对用户上传内容的表现方式做保护处理，对上载内容本身不做任何修改或编辑。若文档所含内容侵犯了您的版权或隐私，请立即通知玖贝云文库，我们立即给予删除！

Observation of superconductivity in the noncentrosymmetric nodal chain semimetal Ba 5In4Bi5 Yuzhe Ma12 Yulong Wang12 Yuxin Wang12 Soham Manni34 Qisheng Lin35 Linlin

相关推荐

开通VIP享超值会员特权

作者详情

相关内容

热门标签

举报选择: