Valleytronic and magneto-optical properties of Janus and conventional <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:mi>TiBrI</mml:mi><mml:mo>/</mml:mo><mml:mi>Cr</mml:mi><mml:msub><mml:mi mathvariant="normal">I</mml:mi><mml:mn>3</mml:mn></mml:msub></mml:mrow></mml:math> and <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:mi>Ti</mml:mi><mml:msub><mml:mi>X</mml:mi><mml:mn>2</mml:mn></mml:msub><mml:mo>/</mml:mo><mml:mi>Cr</mml:mi><mml:msub><mml:mi mathvariant="normal">I</mml:mi><mml:mn>3</mml:mn></mml:msub></mml:mrow></mml:math> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:mo>(</mml:mo><mml:mi>X</mml:mi><mml:mo>=</mml:mo><mml:mi>Br</mml:mi><mml:mo>,</mml:mo><mml:mi mathvariant="normal">I</mml:mi><mml:mo>)</mml:mo></mml:mrow></mml:math> heterostructures
Xiuwen Zhao, Fujun Liu, Junfeng Ren, Fanyao Qu
Abstract
We report magnetic proximity effect, valley splitting (VS), and magneto-optical properties of polar $(\mathrm{TiBrI}/\mathrm{Cr}{\mathrm{I}}_{3})$ and nonpolar ($\mathrm{Ti}{X}_{2}/\mathrm{Cr}{\mathrm{I}}_{3}$, $X=\mathrm{Br},\mathrm{I}$) magnetic van der Waals heterostructures. To properly handle many-body effects, the band structure and excitonic effects are considered on the same footing by carrying out first-principles calculations together with resolving the Bethe-Salpeter equation. We find that an atypical type-III band alignment leads to a sizable magnetic proximity effect as well as giant VS (126 meV). In addition, they can be largely tuned by the polarity of TiXY crystal structure and stacking configuration. Moreover, such a giant magnetic proximity effect drives a switch of spin-band (spin-up and spin-down) ordering of TiBrI, not only in the conduction band, but also surprisingly in the valence band in the vicinity of $K$ or $K$\ensuremath{'} points, which brings out a significant change in exciton emissions. Our results open an avenue for spintronics and nano-optics applications.