Revealing the competition between charge density wave and superconductivity in CsV3Sb5 through uniaxial strain
Revealing the competition between charge density wave and superconductivity in CsV3Sb5 through uniaxial strain
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DOI：
10.1103/physrevb.104.144506
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发表时间：
2021-07
影响因子：
3.7
通讯作者：
Tiema Qian;Morten Christensen;Chaowei Hu;A. Saha;B. M. Andersen;R. Fernandes;T. Birol;N. Ni
中科院分区：
文献类型：
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作者：
Tiema Qian;Morten Christensen;Chaowei Hu;A. Saha;B. M. Andersen;R. Fernandes;T. Birol;N. Ni
本文报道了单轴应变ε对新发现的Kagome超导体CsV3Sb5的影响。在常温下，CSV3Sb5在TCDW=94时表现出电荷密度波(CDW)相变。5K，T_c=3以下的超导体。34K，当单轴应变ε从−0.90%对0。从3.0K到4.0K，T_c单调增加∼33%，得到经验关系式T_c(ε)=3。4+0。56ε+0。12ε2.另一方面，对于ε从−0更改。76%对1。当T cdw(∼)=94时，T cdw从97.5K单调减少10%至87.5K，T cdw(ε)单调减少10%。5−4.72ε−0。60ε2.TC和T CDW对单轴应变的相反响应表明这两个顺序之间存在着强烈的竞争。与流体静压测量结果的比较表明，c轴的变化是导致CDW和超导相变的原因，而应变对六重转动对称性的显式破坏的影响可以忽略不计。结合我们的fi第一原理计算和唯象分析，我们得出结论：T_c随c减小而提高的主要原因是T_(Cdw)的抑制，而不是应变诱导的Modifi阳离子在裸超导参数中的作用。我们认为T-CDW对c轴变化的敏感性源于后者对与CDW相关的M+1和L−-2声子模之间的三线性耦合的影响。总之，c轴晶格参数是CsV3Sb5相图的一个强有力的调谐旋钮，它可以同时受压力和单轴应变的控制。
In this paper we report the effect of uniaxial strain ε applied along the crystalline a axis on the newly discovered kagome superconductor CsV 3 Sb 5 . At ambient conditions, CsV 3 Sb 5 shows a charge-density wave (CDW) transition at T CDW = 94 . 5 K and superconducts below T c = 3 . 34 K. In our paper, when the uniaxial strain ε is varied from − 0 . 90% to 0 . 90% , T c monotonically increases by ∼ 33% from 3.0 to 4.0 K, giving rise to the empirical relation T c ( ε ) = 3 . 4 + 0 . 56 ε + 0 . 12 ε 2 . On the other hand, for ε changing from − 0 . 76% to 1 . 26% , T CDW decreases monotonically by ∼ 10% from 97.5 to 87.5 K with T CDW ( ε ) = 94 . 5 − 4 . 72 ε − 0 . 60 ε 2 . The opposite response of T c and T CDW to the uniaxial strain suggests strong competition between these two orders. Comparison with hydrostatic pressure measurements indicate that it is the change in the c axis that is responsible for these behaviors of the CDW and superconducting transitions, and that the explicit breaking of the sixfold rotational symmetry by strain has a negligible effect. Combined with our first-principles calculations and phenomenological analysis, we conclude that the enhancement in T c with decreasing c is caused primarily by the suppression of T CDW , rather than strain-induced modifications in the bare superconducting parameters. We propose that the sensitivity of T CDW with respect to the changes in the c axis arises from the impact of the latter on the trilinear coupling between the M + 1 and the L − 2 phonon modes associated with the CDW. Overall, our paper reveals that the c -axis lattice parameter, which can be controlled by both pressure and uniaxial strain, is a powerful tuning knob for the phase diagram of CsV 3 Sb 5 .