Shot noise in La_2-xSr_xCuO₄ tunnel junctions

We report shot noise measurement in La_2-xSr_xCuO₄ (LSCO) tunnel junctions with La_2-xSr_xCuO₄ (LCO) tunnel barriers. The LSCO tunnel junctions are grown via molecular beam epitaxy, with different dopings of LSCO ranging from underdoped to optimally doped. Shot noise, which originates from the discrete nature of charge carriers, carries information about the quasiparticles’ effective charge, and correlations in tunneling events. LSCO is a strongly correlated material where the electron-electron interaction is important. LSCO’s normal state is a “strange metal” that may exhibit unconventional quasiparticles at optimal doping, or a pseudogap at underdoping, while LCO is the parent antiferromagnetic Mott insulator. Shot noise specta in LSCO at various temperatures and dopings could be useful in revealing the quasiparticle evolution in different phases of cuprates and provide insights to help understand the non-Fermi liquid behavior in the normal state of these correlated systems.