Adsorption-controlled growth of <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:mi>MnTe</mml:mi><mml:msub><mml:mrow><mml:mo>(</mml:mo><mml:msub><mml:mi>Bi</mml:mi><mml:mn>2</mml:mn></mml:msub><mml:msub><mml:mi>Te</mml:mi><mml:mn>3</mml:mn></mml:msub><mml:mo>)</mml:mo></mml:mrow><mml:mi>n</mml:mi></mml:msub></mml:mrow></mml:math> by molecular beam epitaxy exhibiting stoichiometry-controlled magnetism
Jason Lapano, Lauren Nuckols, Alessandro R. Mazza, Yun-Yi Pai, Jie Zhang, Ben Lawrie, Rob G. Moore, Gyula Eres, Ho Nyung Lee, Mao-Hua Du, T. Zac Ward, Joon Sue Lee, William J. Weber, Yanwen Zhang, Matthew Brahlek
Abstract
We report the growth of the intrinsic magnetic topological system $\mathrm{MnTe}{({\mathrm{Bi}}_{2}{\mathrm{Te}}_{3})}_{n}$ by molecular beam epitaxy. By mapping the temperature and the Bi:Mn flux ratio, it is shown that there is a narrow growth window for the $n=1$ phase $\mathrm{Mn}{\mathrm{Bi}}_{2}{\mathrm{Te}}_{4}$ with $2.0<\mathrm{Bi}:\mathrm{Mn}<2.6$ at 225 \ifmmode^\circ\else\textdegree\fi{}C. Here the films are stoichiometric and excess Bi and Te is not incorporated. At higher flux ratios (Bi:Mn\ensuremath{\ge}4.5) it is found that the $n=2\mathrm{Mn}{\mathrm{Bi}}_{4}{\mathrm{Te}}_{7}$ phase is stabilized. Transport measurements indicate that the $\mathrm{Mn}{\mathrm{Bi}}_{2}{\mathrm{Te}}_{4}$ and $\mathrm{Mn}{\mathrm{Bi}}_{4}{\mathrm{Te}}_{7}$ undergo magnetic transitions around 25 and 10 K, respectively, consistent with antiferromagnetic phases found in the bulk. Further, for Mn-rich conditions (Bi:Mn2), ferromagnetism emerges that exhibits a clear hysteretic state in the Hall effect, which likely indicates Mn-doped $\mathrm{Mn}{\mathrm{Bi}}_{2}{\mathrm{Te}}_{4}$. Understanding how to grow ternary chalcogenide phases is the key to synthesizing new materials and to interface magnetism and topology, which together are routes to realize and control exotic quantum phenomena.