Nonlinear coupling and dissipation in two-dimensional resonators

Micro and nanomechanical resonators are essential to the state-of-the-art communication, data processing, timekeeping, and sensing systems. The discovery of graphene and other two-dimensional (2D) materials has been a profound source of inspiration for the next generation of these devices, owing to their exceptional mechanical, electrical, and...

Mechanics and thermodynamics of suspended two-dimensional membranes

This thesis provides a comprehensive research of both the mechanics and thermodynamics of suspended two-dimensional (2D) membranes, such as tunable mechanical resonance, membrane deformation, heat transport, phonon scattering, and energy dissipation. These characteristics make nanomechanical resonators, made of a suspended 2D membrane, promising...

Magnetic order in 2D antiferromagnets disclosed by spontaneous anisotropic magnetostriction

The temperature dependent order parameter provides important information on the nature of magnetism. Using traditional methods to study this parameter in two-dimensional (2D) magnets remains difficult, however, particularly for insulating antiferromagnetic (AF) compounds. We show that its temperature dependence in AF MPS3 (M(II) = Fe, Co, Ni)...

Thermo-Magnetostrictive Effect for Driving Antiferromagnetic Two-Dimensional Material Resonators

Magnetostrictive coupling has recently attracted interest as a sensitive method for studying magnetism in two-dimensional (2D) materials by mechanical means. However, its application in high-frequency magnetic actuators and transducers requires rapid modulation of the magnetic order, which is difficult to achieve with external magnets,...

Higher-order phenomena in nanomechanics of two-dimensional material membranes

This thesis studies higher-order material properties* and effects in van der Waals crystals, such as anisotropic Young’s modulus, magnetostriction, and non-trivial thermal expansion effects near magnetic and electronic phase transitions, that can affect the nanomechanical motion ofmultilayer two-dimensional (2D) material membranes. These...

Dynamics of interacting graphene membranes

Micro and nanomechanical sensors are indispensable in modern consumer electronics, automotive and medical industries. Gas pressure sensors are currently the most widespread membrane-based micromechanical sensors. By reducing their size, their unit costs and energy consumption drops, making them more attractive for integration in new applications...

Two-dimensional membranes in motion

This thesis revolves around nanomechanical membranes made of suspended two - dimensional materials. Chapters 1-3 give an introduction to the field of 2D-based nanomechanical devices together with an overview of the underlying physics and the measurementtools used in subsequent chapters. The research topics that are discussed can bedivided into...

Graphene gas pumps

We report on the development of a pneumatically coupled graphene membrane system, comprising of two circular cavities connected by a narrow trench. Both cavities and the trench are covered by a thin few-layer graphene membrane to form a sealed dumbbell-shaped chamber. Local electrodes at the bottom of each cavity allow for actuation of each...

Static capacitive pressure sensing using a single graphene drumg

To realize nanomechanical graphene-based pressure sensors, it is beneficial to have a method to electrically readout the static displacement of a suspended graphene membrane. Capacitive readout, typical in micro-electromechanical systems, gets increasingly challenging as one starts shrinking the dimensions of these devices because the expected...

Nanoscale mechanical resonators and oscillators

In this thesis the physics of nanoscale mechanical resonators and oscillators is studied. We discuss two types of resonators. First, a top-down fabricated doubly clamped beam resonator with an integrated piezoelectric actuator is introduced. The second type of resonators are based on layered two-dimensional materials, such as graphene and...

Mechanical systems at the nanoscale

This thesis describes experiments that were done with a wide range of nano(electro)mechanical systems (NEMS). These devices are promising candidates to study mechanics in the quantum regime. The experiments range from AFM measurements on few-layer graphene nanodrums, electrical detection of flexural modes of suspended carbon nanotubes both at...

Carbon nanotube quantum dots

Low temperature electron transport measurements on individual single wall carbon nanotubes are described in this thesis. Carbon nanotubes are small hollow cylinders made entirely out of carbon atoms. At low temperatures (below ~10 K) finite length nanotubes form quantum dots. Because of its small size a quantum dot has a discrete set of energy...

Electrical and mechanical magnetization torques

Only charge degree of freedom is utilized in most electronic devices. The use of the spin degree of freedom is relatively recent. The discovery of the Giant Magnetoresistance (GMR) effect initiated the development of magnetoelectronics - the field that studies effects on electron transport involving the spin degree of freedom. GMR is a very...