Non-charge-transfer origin of Tc Enhancement in a Surface Superconductor Si(111)-(root7xroot3)-In with Adsorbed Organic Molecules

Kenta Yokota; Shunsuke Inagaki; Wenxuan Qian; Ryohei Nemoto; Shunsuke Yoshizawa; Emi Minamitani; Kazuyuki Sakamoto; Takashi Uchihashi

doi:10.7566/jpsj.91.123704

arXiv · 2212.02034

Non-charge-transfer origin of Tc Enhancement in a Surface Superconductor Si(111)-(root7xroot3)-In with Adsorbed Organic Molecules

Kenta Yokota·Shunsuke Inagaki·Wenxuan Qian·Ryohei Nemoto·Shunsuke Yoshizawa·Emi Minamitani·Kazuyuki Sakamoto·Takashi Uchihashi

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Abstract

The effects of adsorption of Zn-phthalocyanine (ZnPc) molecules on the superconductivity of the Si(111)-(root7xroot3)-In surface are studied through transport measurements under ultrahigh vacuum environment. The ZnPc molecules are found to increase the transition temperature Tc by 11% at maximum, which is about 2.7 times the Tc increase previously reported using CuPc. By contrast, angle-resolved photoemission spectroscopy measurements and ab initio calculations show that charge transfer from the In atomic layers to ZnPc is substantially smaller than that to CuPc. This clearly shows that charge transfer should be excluded as the origin of the increase in Tc. The push-back effect induced by physical adsorption of molecules is discussed as a possible mechanism for the Tc enhancement.

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Kenta Yokota, Shunsuke Inagaki, Wenxuan Qian, Ryohei Nemoto, Shunsuke Yoshizawa, Emi Minamitani, Kazuyuki Sakamoto, Takashi Uchihashi. 2022-12-05. Non-charge-transfer origin of Tc Enhancement in a Surface Superconductor Si(111)-(root7xroot3)-In with Adsorbed Organic Molecules. https://doi.org/10.7566/jpsj.91.123704

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