title: Probing thermal expansion of graphene and modal dispersion at low-temperature using graphene nanoelectromechanical systems resonators.
abstract: We use suspended graphene electromechanical resonators to study the variation of resonant frequency as a function of temperature. Measuring the change in frequency resulting from a change in tension, from 300 to 30 K, allows us to extract information about the thermal expansion of monolayer graphene as a function of temperature, which is critical for strain engineering applications. We find that thermal expansion of graphene is negative for all temperatures between 300 and 30 K. We also study the dispersion, the variation of resonant frequency with DC gate voltage, of the electromechanical modes and find considerable tunability of resonant frequency, desirable for applications like mass sensing and RF signal processing at room temperature. With a lowering of temperature, we find that the positively dispersing electromechanical modes evolve into negatively dispersing ones. We quantitatively explain this crossover and discuss optimal electromechanical properties that are desirable for temperature-compensated sensors.
authors.affiliation: Department of Condensed Matter Physics, TIFR, Homi Bhabha Road, Mumbai 400005, India.
authors.forename: Vibhor
authors.initials: V
authors.lastname: Singh
authors.forename: Shamashis
authors.initials: S
authors.lastname: Sengupta
authors.forename: Hari S
authors.initials: HS
authors.lastname: Solanki
authors.forename: Rohan
authors.initials: R
authors.lastname: Dhall
authors.forename: Adrien
authors.initials: A
authors.lastname: Allain
authors.forename: Sajal
authors.initials: S
authors.lastname: Dhara
authors.forename: Prita
authors.initials: P
authors.lastname: Pant
authors.forename: Mandar M
authors.initials: MM
authors.lastname: Deshmukh
mesh_terms: D004867:Equipment Design; D019544:Equipment Failure Analysis; D006108:Graphite / Q000737:chemistry*; D055617:Micro-Electrical-Mechanical Systems / Q000295:instrumentation*; D036103:Nanotechnology / Q000295:instrumentation*; D013696:Temperature; D013814:Thermal Conductivity; D014159:Transducers
chemical_list: D006108:Graphite