Jiuxiang Dai

Light: Science & Applications, Published online: 02 July 2020; doi:10.1038/s41377-020-00356-x

Layering thin films of semiconducting transition metal dichalcogenides with thin-film black phosphorus enhances its ability to emit mid-infrared (MIR) light, which could facilitate MIR light emission investigations and applications. Xiaolong Chen of China’s Southern University of Science and Technology and colleagues layered thin flakes of black phosphorus (BP) with one or the other of a monolayer of tungsten diselenide (WSe2) or a thin film of molybdenum disulfide (MoS2). Thin-film BP is considered a promising MIR material, with potential applications in MIR photodetection and optical modulation. WSe2 efficiently transferred light energy to the BP, enhancing its MIR photoluminescence by up to 192%. On the other hand, the interface created by layering BP with MoS2 enabled the formation of a MIR light-emitting diode at room temperature.

Author(s): Huanhuan Yang, C. Wang, Tianlin Yu, Yunshan Cao, and Peng Yan

We present a theoretical mapping to show that a ferromagnet with gain (loss) is equivalent to an antiferromagnet with an equal amount of loss (gain). Our findings indicate a novel first-order ferromagnet-antiferromagnet phase transition by tuning the gain-loss parameter. As an appealing application,...

[Phys. Rev. Lett. 121, 197201] Published Mon Nov 05, 2018

Nature Nanotechnology 12, 757 (2017). doi:10.1038/nnano.2017.68

Authors: Chuan Zhao, Tenzin Norden, Peiyao Zhang, Puqin Zhao, Yingchun Cheng, Fan Sun, James P. Parry, Payam Taheri, Jieqiong Wang, Yihang Yang, Thomas Scrace, Kaifei Kang, Sen Yang, Guo-xing Miao, Renat Sabirianov, George Kioseoglou, Wei Huang, Athos Petrou & Hao Zeng

Exploiting the valley degree of freedom to store and manipulate information provides a novel paradigm for future electronics. A monolayer transition-metal dichalcogenide (TMDC) with a broken inversion symmetry possesses two degenerate yet inequivalent valleys, which offers unique opportunities for valley control through the helicity of light. Lifting the valley degeneracy by Zeeman splitting has been demonstrated recently, which may enable valley control by a magnetic field. However, the realized valley splitting is modest (∼0.2 meV T–1). Here we show greatly enhanced valley spitting in monolayer WSe2, utilizing the interfacial magnetic exchange field (MEF) from a ferromagnetic EuS substrate. A valley splitting of 2.5 meV is demonstrated at 1 T by magnetoreflectance measurements and corresponds to an effective exchange field of ∼12 T. Moreover, the splitting follows the magnetization of EuS, a hallmark of the MEF. Utilizing the MEF of a magnetic insulator can induce magnetic order and valley and spin polarization in TMDCs, which may enable valleytronic and quantum-computing applications.