Structural and magnetic properties of molecular beam epitaxy grown chromium selenide thin films
Anupam Roy, Rik Dey, Tanmoy Pramanik, Amritesh Rai, Ryan Schalip, Sarmita Majumder, Samaresh Guchhait, Sanjay K. Banerjee
Abstract
Chromium selenide thin films were grown epitaxially on $\mathrm{A}{\mathrm{l}}_{2}{\mathrm{O}}_{3}(0001)$ and Si(111)-(7 \ifmmode\times\else\texttimes\fi{} 7) substrates using molecular beam epitaxy. Sharp streaks in reflection high-energy electron diffraction and triangular structures in scanning tunneling microscopy indicate flat smooth film growth along the $c$ axis, which is very similar to that from a hexagonal surface. The x-ray diffraction pattern confirms the growth along the $c$ axis with a $c$-axis lattice constant of 17.39 \AA{}. The grown film is semiconducting, having a small band gap of about 0.034 eV, as calculated from the temperature-dependent resistivity. The antiferromagnetic nature of the film with a N\'eel temperature of about 40 K is estimated from the magnetic exchange bias measurements. A larger out-of-plane exchange bias, along with a smaller in-plane exchange bias is observed below 40 K. Exchange bias training effects are analyzed based on different models and are observed to be following a modified power-law decay behavior.