We have synthesized single crystal samples of Ca₃Rh₄Sn₁₃ by flux method, measured its transport, magnetic and thermodynamic properties. Experimental results show a bulk superconducting transition at T_c ∼ 8.4 K, employing the measured values of the specific heat C_p(T), the upper critical field H_c2, and the lower critical field H_c1, we estimated the density of the state at the Fermi level, electron-phonon coupling constant λ_ep, thermodynamic critical field H_c(0), Wilson ratio R_w, coherence length ξ (0), penetration depth λ(0), the Ginzburg-Landau parameter κ(0) and the Pauli limiting field H_Pauli. It is identified that σT⁵ term plays an indispensable role in C_p(T) of this kind of caged compound, characterizing the anharmonic oscillation of the Sn atom at the center of the icosahedron. The specific heat jumps at Tc, ΔC/γTc = 2.63, suggests that Ca₃Rh₄Sn₁₃ is a moderately coupled superconductor. Above 2 K the electronic specific heat exhibits the exponential behavior, implies Ca₃Rh₄Sn₁₃ owns a superconducting gap without nodes. The fact that H_c2(0) is much smaller than its H_Pauli could exclude the possibility of A_1u triplet component in its ground state, further research should focus on the intricate interacting between short-range charge density waves and the unconventional $A_{1g}^{+-}$$A_{1g}^{+-}$ singlet pairing mechanism for Ca₃Rh₄Sn₁₃.

中文翻译：

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A15 三元化合物 Ca3Rh4Sn13 的合成、物理性质和可能的配对机制

我们用磁通量法合成了 Ca ₃ Rh ₄ Sn ₁₃ 的单晶样品，测量了它的输运、磁性和热力学性质。实验结果表明，在 T _c ∼ 8.4 K 处存在体超导转变，利用比热 C _p （T） 的测量值、上临界场 H _c2 和下临界场 H _c1, 的测量值，我们估计了费米能级的状态密度、电子-声子耦合常数 λ _ep 、热力学临界场 H _c （0）、威尔逊比 R _w 、相干长度 ξ （0）、穿透深度 λ（0）、Ginzburg-Landau 参数 κ（0） 和 Pauli 极限场 H _Pauli 。结果表明，σT ⁵ 项在这种笼状化合物的 C _p （T） 中起着不可或缺的作用，表征了二十面体中心 Sn 原子的异谐振荡。Tc 处的比热跃迁 ΔC/γTc = 2.63 表明 Ca ₃ Rh ₄ Sn ₁₃ 是一种中等耦合的超导体。高于 2 K 的电子比热表现出指数行为，这意味着 Ca ₃ Rh ₄ Sn ₁₃ 拥有没有节点的超导间隙。H _c2 （0） 远小于其 H _Pauli 的事实可以排除 A _1u 三重态分量在其基态下的可能性，进一步的研究应集中在短程电荷密度波和 Ca ₃ Rh ₄ Sn ₁₃ 的非常规 $A_{1g}^{+-}$ 单重态配对机制之间的复杂相互作用上。