Samarium Substitution and Epitaxial Strain in La₂SmNi₂O₇ Thin Films

Min-Hong Wang^1*, Sung-Chih Chiu¹, Cheng-Yu Yu¹, Chun-Ting Kuo¹, Yu-Chieh Wang¹, Yu-Wei Cheng¹, Pei-Shan Tsai¹, Jhao-Wei Su¹, Wen-Yen Tzeng², Jiunn-Yuan Lin¹

¹Institute of Physics, National Yang Ming Chiao Tung University, Hsinchu City, Taiwan
²Department of Applied Physics, National Pingtung University, Pingtung County, Taiwan

* Presenter:Min-Hong Wang, email:whitent.sc13@nycu.edu.tw

Superconductivity in bulk La₃Ni₂O₇ at temperatures approaching 80 K highlights the importance of interlayer coupling and orbital polarization. Building on the La₃Ni₂O₇ /La₂PrNi₂O₇ series, we introduce Samarium substitution and fabricate the epitaxial thin films of La₂SmNi₂O₇ using pulsed laser deposition on substrates with adjustable strain. To explore the electronic structure, we employ Ni L-edge and O K-edge X-ray absorption spectroscopy. Raman spectroscopy will track Eg/A1g and Ni–O phonon shifts in response to Sm and strain, serving as indicators of structural tuning and interlayer coupling. Simultaneously, the temperature-dependent resistivity of the selected films is reported and the scenario of the charge density wave (CDW) in La₂SmNi₂O₇ thin films. Together, these controls may offer a pathway to increase Tc and hopefully achieve ambient-pressure superconductivity more readily.

Keywords: La₃Ni₂O₇, La₂SmNi₂O₇, Charge-density wave