Investigating Strain-Induced Emergence of Landau Levels in Intercalated Graphene

Swati Kanojia^1*, Liang-Wei Lan¹, Bheim M. Llona¹, Chien-Cheng Kuo¹

¹Physics, National Sun-Yat sen University, Gushan, Kaohsiung, Taiwan

* Presenter:Swati Kanojia, email:swatifiziks@gmail.com

Graphene's Dirac fermions exhibit unconventional behaviors under external influences like electric fields, magnetic fields, strain, and diverse substrates[1]. These effects yield intriguing phenomena, such as the quantum Hall effect, Landau levels, and novel electronic states, making graphene a versatile material for research and potential applications[2]. In our previous study, we introduced strain with periodic z potential vector by the Moiré structure on graphene/Ru(0001). This manipulation led to the clear observation of Landau level splitting in the strained graphene, suggesting the presence of an equivalent magnetic field known as the pseudo-magnetic field. It does not change the momentum of excited electrons which is a promising template for electron technique measurement. Furthermore, a noteworthy aspect is the behavior of strained graphene in a real magnetic field. Certain interactions and possible hybridizations in the co-existence of real magnetic and pseudo-magnetic fields in graphene are not revealed. Understanding the hidden mechanism provides us with insight into graphene spintronics[3][4].

In this investigation, cobalt is employed as a magnetic intercalant between graphene and Ru(0001). The coverage is controlled less than a monolayer which performs the strained graphene surface with and without Co simultaneously for comparison. Scanning tunneling microscopy (STM) and scanning tunneling spectroscopy (STS) were utilized to measure the structural and electronic properties of the strained graphene with and without cobalt intercalation. Cobalt intercalation induces a dislocation of the moiré pattern, which can be attributed to the strain-induced changes within the graphene layer. The most remarkable discovery stems from STS measurements which exhibit separated energy levels. The introduction of Co intercalated islands has led to a notable displacement of the peaks towards higher energy levels. Further insights into the data can be presented during the talk.


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Keywords: Graphene, Scanning Tunneling Microscopy(STM), Intercalation, Landau Levels, Pseudomagnetic field