Probing magnetic-proximity-effect enlarged valley splitting in monolayer WSe2 by photoluminescence
valley splitting, transition metal dichalcogenides, magnetic proximity effect, heterostructure, magnetic exchange field
ABSTRACT Possessing a valley degree of freedom and potential in information processing by manipulating valley features (such as valley splitting), group-VI monolayer transition metal dichalcogenides have attracted enormous interest. This valley splitting can be measured based on the difference between the peak energies of σ+ and σ− polarized emissions for excitons or trions in direct band gap monolayer transition metal dichalcogenides under perpendicular magnetic fields. In this work, a well-prepared heterostructure is formed by transferring exfoliated WSe2 onto a EuS substrate. Circular-polarization-resolved photoluminescence spectroscopy, one of the most facile and intuitive methods, is used to probe the difference of the gap energy in two valleys under an applied out-of-plane external magnetic field. Our results indicate that valley splitting can be enhanced when using a EuS substrate, as compared to a SiO2/Si substrate. The enhanced valley splitting of the WSe2/EuS heterostructure can be understood as a result of an interfacial magnetic exchange field originating from the magnetic proximity effect. The value of this magnetic exchange field, based on our estimation, is approximately 9 T. Our findings will stimulate further studies on the magnetic exchange field at the interface of similar heterostructures.
Tsinghua University Press
Chenji Zou,Chunxiao Cong,Jingzhi Shang,Chuan Zhao,Mustafa Eginligil,Lishu Wu,Yu Chen,Hongbo Zhang,Shun Feng,Jing Zhang,Hao Zeng,Wei Huang,Ting Yu, Probing magnetic-proximity-effect enlarged valley splitting in monolayer WSe2 by photoluminescence. NanoRes.2018, 11(12): 6252–6259