Electronic structure, Fermi surfaces, and electron-phonon coupling in La-doped Sr$_{2}$TiO$_{4}$ and SrTiO$_{3}$*

Sr$_{2}$TiO$_{4}$ is a quasi-two-dimensional Ruddlesden-Popper structure analogue to SrTiO$_{3}$, and is isostructural with the cuprate parent compound La$_{2}$CuO$_{4}$. Although the electronic structure of SrTiO$_{3}$ has been well-explored due to its importance in oxide electronics, little is known about the electronic properties of Sr$_{2}$TiO$_{4}$. To investigate this, we synthesized epitaxial La doped Sr$_{2}$TiO$_{4}$ and SrTiO$_{3}$ films on (100) LSAT substrates by molecular beam epitaxy (MBE) and investigated the electronic structure using angle-resolved photoemission spectroscopy (ARPES). The electronic structure of 5{\%} La doped Sr$_{2}$TiO$_{4}$ shows a single electron like band with mostly Ti-3d$_{xy}$ character dispersing across the Fermi surface which corresponds well with LDA calculations. This is in contrast to doped SrTiO$_{3}$ where all three t2g bands are degenerate. We also observed signatures of strong electron-phonon coupling in the quasi-two-dimensional Sr$_{2}$TiO$_{4}$ materials which appear to be absent in three-dimensional SrTiO$_{3}$.