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)...

Controlling the anisotropy of a van der Waals antiferromagnet with light

Van der Waals magnets provide an ideal playground to explore the fundamentals of low-dimensional magnetism and open opportunities for ultrathin spin-processing devices. The Mermin-Wagner theorem dictates that as in reduced dimensions isotropic spin interactions cannot retain long-range correlations, the long-range spin order is stabilized by...

High-frequency gas effusion through nanopores in suspended graphene

Porous, atomically thin graphene membranes have interesting properties for filtration and sieving applications. Here, graphene membranes are used to pump gases through nanopores using optothermal forces, enabling the study of gas flow through nanopores at frequencies above 100 kHz. At these frequencies, the motion of graphene is closely...

Tunable Strong Coupling of Mechanical Resonance between Spatially Separated FePS₃Nanodrums

Coupled nanomechanical resonators made of two-dimensional materials are promising for processing information with mechanical modes. However, the challenge for these systems is to control the coupling. Here, we demonstrate strong coupling of motion between two suspended membranes of the magnetic 2D material FePS3. We describe a tunable...

Study of charge density waves in suspended 2H-TaS₂ and 2H-TaSe₂ by nanomechanical resonance

The charge density wave (CDW) state in van der Waals systems shows interesting scaling phenomena as the number of layers can significantly affect the CDW transition temperature, T_CDW. However, it is often difficult to use conventional methods to study the phase transition in these systems due to their small size and sensitivity to...

Chemical Design and Magnetic Ordering in Thin Layers of 2D Metal-Organic Frameworks (MOFs)

Through rational chemical design, and thanks to the hybrid nature of metal-organic frameworks (MOFs), it is possible to prepare molecule-based 2D magnetic materials stable at ambient conditions. Here, we illustrate the versatility of this approach by changing both the metallic nodes and the ligands in a family of layered MOFs that allows the...

Nanomechanical probing and strain tuning of the Curie temperature in suspended Cr₂Ge₂Te₆-based heterostructures

Two-dimensional magnetic materials with strong magnetostriction are attractive systems for realizing strain-tuning of the magnetization in spintronic and nanomagnetic devices. This requires an understanding of the magneto-mechanical coupling in these materials. In this work, we suspend thin Cr₂Ge₂Te₆ layers...

Sensitive capacitive pressure sensors based on graphene membrane arrays

The high flexibility, impermeability and strength of graphene membranes are key properties that can enable the next generation of nanomechanical sensors. However, for capacitive pressure sensors, the sensitivity offered by a single suspended graphene membrane is too small to compete with commercial sensors. Here, we realize highly sensitive...

Magnetic order in 2D antiferromagnets revealed 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. Here, we show that its temperature dependence in AF MPS₃ (M...

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,...

Tuning heat transport in graphene by tension

Heat transport by acoustic phonons in two-dimensional (2D) materials is fundamentally different from that in 3D crystals because the out-of-plane phonons propagate in a unique way that strongly depends on tension and bending rigidity. Here, using optomechanical techniques, we experimentally demonstrate that the heat transport time in...

Ultrathin Piezoelectric Resonators Based on Graphene and Free-Standing Single-Crystal BaTiO₃

Suspended piezoelectric thin films are key elements enabling high-frequency filtering in telecommunication devices. To meet the requirements of next-generation electronics, it is essential to reduce device thickness for reaching higher resonance frequencies. Here, the high-quality mechanical and electrical properties of graphene electrodes...

Magnetic and electronic phase transitions probed by nanomechanical resonators

The reduced dimensionality of two-dimensional (2D) materials results in characteristic types of magnetically and electronically ordered phases. However, only few methods are available to study this order, in particular in ultrathin insulating antiferromagnets that couple weakly to magnetic and electronic probes. Here, we demonstrate that...

Highly anisotropic mechanical and optical properties of 2D layered As₂S₃ membranes

Two-dimensional (2D) materials with strong in-plane anisotropy are of interest for enabling orientation-dependent, frequency-tunable, optomechanical devices. However, black phosphorus (bP), the 2D material with the largest anisotropy to date, is unstable as it degrades in air. In this work we show that As₂S₃ is an...

Sealing graphene nanodrums

Despite theoretical predictions that graphene should be impermeable to all gases, practical experiments on sealed graphene nanodrums show small leak rates. Thus far, the exact mechanism for this permeation has remained unclear, because different potential leakage pathways have not been studied separately. Here, we demonstrate a sealing method...

Gas sensing with porous nanodrums