Nodeless superconductivity in the SnAs-based van der Waals-type superconductor NaSn ₂ As ₂

Abstract

We grew the single crystals of the SnAs-based van der Waals (vdW)-type superconductor NaSn2As2 and systematically measured its resistivity, specific heat, and ultralow-temperature thermal conductivity. The superconducting transition temperature Tc = 1.60 K of our single crystal is 0.3 K higher than that previously reported. A weak but intrinsic anomaly situated at 193 K is observed in both resistivity and specific heat, which likely arises from a charge-densitywave (CDW) instability. Ultralow-temperature thermal conductivity measurements reveal a fullygapped superconducting state with a negligible residual linear term in zero magnetic field, and the field dependence of κ0/T further suggests NaSn2As2 is an s-wave superconductor.

Crystal Structure and Electrical/thermal Transport Properties of Li1-xSn2+xP2 and Its Performance as a Li-Ion Battery Anode Material

“…[17][18][19][20][21] The residual resistivity ratio (300 K)/(0.5 K) is estimated to be 1.3, which is comparable to those of related materials. [13][14][15]17,18,20,21,35 Due to the layered structure of Li1-xSn2+xP2, we investigated its anisotropy in resistivity with respect to uniaxial hot pressing direction above room temperature. As shown in Figure 4(a), the anisotropy in the present samples is not significant.…”

Crystal Structure and Electrical/thermal Transport Properties of Li1-xSn2+xP2 and Its Performance as a Li-Ion Battery Anode Material

“…No superconducting transition is observed down to 0.5 K, unlike for Na1-xSn2P2 and NaSn2As2. [17][18][19][20][21] The residual resistivity ratio (300 K)/(0.5 K) is estimated to be 1.3, which is comparable to those of related materials. [13][14][15]17,18,20,21,35 Due to the layered structure of Li1-xSn2+xP2, we investigated its anisotropy in resistivity with respect to uniaxial hot pressing direction above room temperature.…”

“…16 It has also been demonstrated that NaSn2As2 and Na1-xSn2P2 show superconducting transitions, meaning that these compounds can also be categorized as novel layered superconductors. [17][18][19][20][21] As well as these ternary-phase materials, the binary tin phosphide Sn4P3 has been investigated as a rechargeable battery anode material. [22][23][24][25][26][27][28][29][30][31] For example, the high reversible capacity of 850 mA•h•g −1 has been achieved for a Na-ion battery with a Sn4P3/C composite anode.…”

Thermoelectric Properties of the As/P-Based Zintl Compounds EuIn2As2−xPx (X = 0 to 2) and SrSn2As2

“…[41][42][43] In addition to being thermoelectric materials, these compounds are interesting because they undergo superconducting transitions at low temperatures. [44][45][46][47][48] compounds EuIn2As2−xPx (x = 0 to 2) and SrSn2As2. In the early stage of this work, we first investigated the thermoelectric properties of SrSn2As2.…”