arXiv subjects

Hasan Sadat Nabi

Publications and source records attributed to Hasan Sadat Nabi.

2 recordsLinked to original sources

arXiv2009

Effect of strain on the stability and electronic properties of ferrimagnetic Fe$_{2-x}$Ti$_x$O$_3$ heterostructures from correlated band theory

Based on density functional theory (DFT) calculations including an on-site Hubbard $U$ term we investigate the effect of substrate-induced strain on the properties of ferrimagnetic Fe$_2$O$_3$-FeTiO$_3$ solid solutions and heterostructures. While the charge compensation mechanism through formation of a mixed \fetw, \feth-contact layer is unaffected, strain can be used to tune the electronic properties of the system, e.g. by changing the position of impurity levels in the band gap. Straining hematite/ilmenite films at the lateral parameters of Al$_{2}$O$_{3}$(0001), commonly used as a substrate, is found to be energetically unfavorable as compared to films on Fe$_{2}$O$_{3}$(0001) or FeTiO$_{3}$(0001)-substrates.

cond-mat.mtrl-sci↗

arXiv2008

Interface magnetism in Fe2O3/FeTiO3-heterostructures

To resolve the microscopic origin of magnetism in the Fe2O3/FeTiO3-system, we have performed density functional theory calculations taking into account on-site Coulomb repulsion. By varying systematically the concentration, distribution and charge state of Ti in a hematite host, we compile a phase diagram of the stability with respect to the end members and find a clear preference to form layered arrangements as opposed to solid solutions. The charge mismatch at the interface is accommodated through Ti4+ and a disproportionation in the Fe contact layer into Fe2+, Fe3+, leading to uncompensated moments in the contact layer and giving first theoretical evidence for the lamellar magnetism hypothesis. This interface magnetism is associated with impurity levels in the band gap showing halfmetallic behavior and making Fe2O3/FeTiO3 heterostructures prospective materials for spintronics applications.

cond-mat.mtrl-sci↗