paper

Dome structure in pressure dependence of superconducting transition temperature for HgBaCaCuO -- Studies by low-energy effective Hamiltonian

arXiv:2312.16402 · doi:10.1103/PhysRevResearch.6.023163

Abstract

The superconducting (SC) cuprate HgBaCaCuO (Hg1223) has the highest K (the experimental SC transition temperature at optimal hole doping) among cuprates at ambient pressure . increases under pressure and reaches K at GPa, then decreases with increasing . To understand the microscopic origin of this dome-like dependence of , we consider the low-energy effective Hamiltonian (LEH) for the antibonding (AB) Cu/O band. In the AB LEH for cuprates with laminated CuO planes between block layers, it was proposed that , where is the nearest neighbor hopping and the SC order parameter at optimal hole doping mainly depends on ( is the onsite effective Coulomb repulsion): is maximal at and decreases sharply with decreasing for . In this paper, we show that (I) increases with , whereas (II) decreases with in the AB LEH of Hg1223. Based on (I,II), the dome-like dependence of emerges if we assume (A) Hg1223 with obeys , and (B) at and at by including expected corrections to our calculation. The consequence of (A,B) is the following: At , the increase in is accounted for by (I) whereas is insensitive to (II) and hence to . At , the decrease in is accounted for by (II): The rapid decrease in with decreasing for dominates over (I). We support (A,B) based on studies of other cuprates.

23 pages, 15 figures, 5 tables. The Supplemental Material contains the complete list of parameters for selected effective Hamiltonians that are presented in the main text and in Appendix C. This Supplemental Material may be obtained from the authors upon request

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